KR20140093182A - Protective sheet for chemical solution treatment - Google Patents

Abstract

Provided in the present invention is a protective sheet for liquid chemical treatment, which includes adhesive layers placed on a base material and one side of the base material. The adhesive forming the adhesive layer is an acrylic based adhesive having an acrylic based polymer as a main component. The protective sheet has a low speed peeling strength of 0.1 N/20 mm or greater measured at a tension speed of 300 mm/minute, and has a high speed peeling strength of 3 N/20 mm or less measured at a tension speed of 10 m/minute. In addition, the gel fraction of the acrylic based adhesive is between 25 and 70 mass%.

Description

PROTECTIVE SHEET FOR CHEMICAL SOLUTION TREATMENT [0002]

The present application claims priority based on Japanese Patent Application No. 2013-005898, filed on January 17, 2013, the entire contents of which are incorporated herein by reference.

The present invention relates to a protective sheet for chemical liquid treatment. And more particularly to a protective sheet for chemical liquid treatment which masks an untreated portion (a portion to which influence of a chemical liquid is to be excluded) when an adherend is treated with a chemical liquid.

The pressure-sensitive adhesive sheet for masking the non-treatment object portion (the portion to which the influence of the chemical liquid is to be excluded) of the adherend when the adherend (the material to be treated) is treated with the chemical liquid typically has a film-like pressure- And a base material (support base material) for supporting the pressure sensitive adhesive, wherein the pressure sensitive adhesive is adhered to the adherend. Such a pressure-sensitive adhesive sheet for chemical liquid treatment (hereinafter also referred to as a " protective sheet for chemical liquid treatment " or simply referred to as a " protective sheet ") may be formed by, for example, An etching process for partially etching the surface of a metal with a chemical solution (etching solution), a connection terminal portion of a circuit board (a printed board, a flexible printed board (FPC), or the like) It can be suitably used in a plating process for plating. Documents relating to this kind of technology include Japanese Patent Application Laid-Open No. 2010-53346, Japanese Patent Application Laid-Open No. 2003-82299, and Japanese Patent Application Laid-Open No. 2009-209223.

Japanese Patent Application Laid-Open No. 2010-53346 Japanese Patent Application Laid-Open No. 2003-82299 Japanese Patent Application Laid-Open No. 2009-209223

The surface of the protective sheet (the surface directly exposed to the chemical liquid, that is, the surface opposite to the side attached to the adherend) or the outer edge of the protective sheet (hereinafter also referred to as the end surface or the side surface) It is required to prevent intrusion of a chemical liquid, that is, to prevent the penetration of a chemical liquid (sealability).

Here, the penetration of the chemical liquid from the outer edge of the protective sheet can also occur from the interface between the adhesive of the protective sheet and the adherend. In order to prevent the penetration of the chemical solution from such an interface, the property (adhesion) of the pressure-sensitive adhesive of the protective sheet to the surface of the adherend without gaps is important. However, if a pressure sensitive adhesive having a high peel strength (adhesive force) is used to improve the adhesion of the adherend to the surface, the peeling workability when peeling off the protective sheet unnecessary after the chemical liquid treatment is deteriorated. For example, at the time of peeling, the protective sheet itself tends to break or the adhesive of the protective sheet tends to remain on the surface of the adherend (so-called adhesive residue). In addition, there is a concern that damage to the adherend or a structure (for example, an ITO film) on the surface of the adherend may be caused by an increase in the load applied to the adherend upon peeling. In view of such circumstances, when a protective sheet having a higher peeling strength (peeling strength) is used, it may be necessary to perform a peeling operation with more care, so that the efficiency of the peeling work tends to be lowered.

It is therefore an object of the present invention to provide a chemical-solution-treating protective sheet capable of both preventing chemical-solution penetration and peeling workability from an adherend at a high level.

The protective sheet for chemical liquid treatment provided by this specification comprises a base material and a pressure-sensitive adhesive layer disposed on one side of the base material. The pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive, hereinafter the same) constituting the pressure-sensitive adhesive layer is typically an acrylic pressure-sensitive adhesive mainly comprising an acrylic polymer. The protective sheet preferably has a low peel strength (P _L ) of 0.1 N / 20 mm or more measured at a peel angle of 180 ° and a tensile rate of 300 mm / min after 30 minutes from being attached to the glass plate. The protective sheet preferably has a high peel strength (P _H ) of 3 N / 20 mm or less as measured at a peel angle of 180 ° and a tensile speed of 10 m / min after 30 minutes from adhering to the glass plate. The gel fraction of the acrylic pressure sensitive adhesive is preferably 25 mass% or more and 70 mass% or less.

In the technique disclosed in this specification, the low peel strength (P _L ) represents the degree of difficulty (resistance) of peeling of the protective sheet against the stress applied relatively slowly, and is recognized as a characteristic relating to the adhesion of the pressure- . On the other hand, the high peel strength (P _H ) can be grasped as the peel strength assuming that the unnecessary protective sheet is finely peeled off from an adherend (for example, an adherend after the protective sheet is adhered and treated).

The protective sheet exhibits good adhesion such that the low rate peel strength (P _L ) is 0.1 N / 20 mm or more with respect to the surface of the adherend (typically, adherend having a surface including a polar material such as glass). Therefore, the penetration of the chemical liquid from the interface between the pressure-sensitive adhesive and the adherend can be effectively prevented, and the chemical liquid penetration prevention property is excellent. Further, since the high peel strength (P _H ) is suppressed to 3 N / 20 mm or less, it is difficult for the protective sheet to break (scrape) or remain in the pressure-sensitive adhesive when peeling the protective sheet from the adherend, It is also small. Therefore, the peeling workability is excellent. Further, since the gel fraction of the pressure-sensitive adhesive is in the range of 25 mass% to 70 mass%, it is possible to balance both the prevention of the penetration of the chemical liquid and the peeling workability.

The protective sheet preferably has a ratio (P _L / P _H ) of the low peel strength (P _L ) to the high peel strength (P _H ) of more than 0.5. Such a protective sheet is light in peeling at high speed as compared with heavy peeling at low speed. Therefore, even if the gel fraction of the pressure-sensitive adhesive is less than 60 mass% (typically greater than 25 mass% and less than 60 mass%) for the purpose of enhancing the adhesion, for example, when the protective sheet is peeled off, breakage of the protective sheet, And the load applied to the adherend is small. Therefore, the chemical liquid intrusion prevention and peeling workability can be made compatible at a higher level.

In one preferred form of the technique disclosed in this specification, the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition comprising an acrylic polymer and a release-modifying agent. Here, the release control agent is the balance of the release characteristics, specifically, the low-speed peel strength (P _L) and a high-speed peel strength (P _H) of the protective sheet (adhesive sheet) having the pressure-sensitive adhesive layer formed from the composition by being included in the pressure sensitive adhesive composition And the like. The balance between the low speed peeling strength (P _L ) and the high peeling strength (P _H ) can be grasped by the value of P _L / P _H. The protective sheet of the above-mentioned type can have a good balance of P _L and P _H , and can be compatible with the chemical liquid penetration prevention performance and the peeling workability at a high level.

The acrylic pressure-sensitive adhesive preferably contains a monomer unit derived from a carboxylic acid vinyl ester in a proportion of higher than 20 mass%. As a result, a protective sheet which can achieve both a chemical liquid penetration prevention performance and a peeling workability at a higher level can be realized. The monomer unit derived from the carboxylic acid vinyl ester may be contained in the acrylic polymer, may be contained in the polymer different from the acrylic polymer, or may be contained in both of them.

In a preferred form, the acrylic polymer as a main component of the acrylic pressure-sensitive adhesive is synthesized by polymerizing (typically, solution polymerization) a monomer raw material comprising alkyl (meth) acrylate and a carboxylic acid vinyl ester. In other words, the acrylic polymer includes a monomer unit derived from an alkyl (meth) acrylate and a monomer unit derived from a carboxylic acid vinyl ester. The content of the carboxylic acid vinyl ester in the monomer raw material is preferably higher than 20 mass%.

According to this aspect, a protective sheet capable of achieving both a chemical liquid penetration preventing performance and a peeling workability at a high level can be realized.

The pressure-sensitive adhesive layer in the technique disclosed in this specification is preferably formed of a pressure-sensitive adhesive composition comprising the acrylic polymer and the isocyanate-based crosslinking agent. The protective sheet having such a pressure-sensitive adhesive layer can be compatible with the chemical-solution intrusion prevention property and the peeling workability at a higher level.

1 is a cross-sectional view schematically showing an example of the structure of a chemical liquid treatment protective sheet.
2 is a cross-sectional view schematically showing another structural example of a chemical liquid treatment protective sheet.

Hereinafter, preferred embodiments of the present invention will be described. The matters necessary for the practice of the present invention may be understood as design matters of a person skilled in the art based on the prior art in the field other than those specifically mentioned in this specification. The present invention can be carried out based on the contents disclosed in this specification and the technical knowledge in the field. The " sheet " in this specification includes a film which is considered to be relatively thinner in thickness than a sheet, or a tape which is generally referred to as an adhesive tape.

≪ Overall structure of protective sheet >

The protective sheet disclosed in this specification includes a base material and a pressure-sensitive adhesive layer disposed on at least one surface of the base material. The shape of the protective sheet may be a sheet shape, and may be, for example, a roll shape, a single plate with a separator, or the like.

A typical configuration example of such a protective sheet is schematically shown in Fig. The protective sheet 10 includes a sheet-like base material 1 (for example, a resin sheet base material) 1 and a pressure-sensitive adhesive layer 2 disposed on one side (one side) thereof. The surface of the protective sheet 10 on the side of the pressure-sensitive adhesive layer 2 is treated with a predetermined portion of the adherend (the portion to be protected, typically, the influence of the chemical liquid is excluded) before the adherend (Hereinafter also referred to as a " non-treatment target portion "). Thereby protecting the non-treatment target portion from the chemical liquid. The protective sheet 10 before use (that is, before adhering to an adherend) typically has a surface (adhered surface to an adherend, hereinafter also referred to as adherend surface) of the pressure-sensitive adhesive layer 2, May be in a form in which at least the side of the pressure-sensitive adhesive layer (2) is protected by the release liner (3) which is a release surface. Or the other surface of the base material 1 (the back surface of the surface on which the pressure-sensitive adhesive layer 2 is disposed) is a peeled surface and the protective sheet 10 is rolled into a roll shape so that the pressure- And the surface (adhesive surface) thereof may be protected. Further, the protective sheet may be a double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer disposed on each side of the substrate. In this case, the attachment surface (adhesion surface) of each pressure-sensitive adhesive layer to the adherend may be protected by a release liner at least on the side of the pressure-sensitive adhesive layer being peeled, or alternatively, Or may be wound in a roll shape.

As the base material used for the protective sheet, known base materials such as film or sheet can be appropriately selected and used. The material of the substrate is not particularly limited. For example, a substrate formed of a metal material (aluminum or the like), a substrate formed of a resin material, or a substrate formed of such a composite material (e.g., a plastic film obtained by depositing a metal on one surface).

Examples of suitable examples of the base material in the present invention include polyolefins such as polyethylene (PE), polypropylene (PP), ethylene propylene rubber (EPR), ethylene-propylene-butene copolymer and ethylene- Suzy; Polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate; Polyamide resin (PA); Polyimide resin (PI); Polyphenylene sulfide resin (PPS); Polycarbonate resin (PC); Polyurethane resin (PU); Ethylene-vinyl acetate resin (EVA); Fluorine resins such as polytetrafluoroethylene (PTFE); Acrylic resin; (Plastic film) containing a resin material such as polyvinyl chloride. The substrate may be a plastic film containing a resin material containing one kind of such resin alone or a plastic film containing a resin material blended with two or more kinds of resin materials.

Here, the plastic film typically refers to a non-porous plastic film and is a concept distinct from a woven fabric or a nonwoven fabric. As the base material of the protective sheet disclosed in this specification, both non-stretched plastic film and stretched plastic film can be used. The stretched plastic film may be a uniaxially stretched plastic film or a biaxially stretched plastic film.

From the viewpoint of having suitable flexibility among them, a polyolefin resin (for example, a polyolefin resin containing at least one of polyolefin resins such as PP, PE and EPR, or a blend of two or more kinds) Resin (for example, PET). The polyolefin resin or polyester resin has suitable flexibility. The protective sheet provided with such a base material made of a resin material is easy to follow the step, for example, even when the surface step of the adherend is present. That is, the surface shape followability is high. As a result, it is difficult to form a path (gap) for penetration of the chemical liquid between the pressure-sensitive adhesive of the protective sheet and the adherend. Therefore, it is suitable as a base material of a protective sheet for chemical liquid treatment.

Further, the step may be derived from a structure formed on the surface of the adherend. As the adherend having such a structure, for example, a transparent conductive film (for example, an ITO film (indium tin oxide film)) or the like is partially formed on a surface such as used for a tablet type personal computer, a cellular phone, an organic LED (light emitting diode) A glass substrate on which an FPC is mounted.

As the base material of the protective sheet disclosed in this specification, those containing a resin material having high acid resistance can be preferably adopted. Such a substrate is hardly swollen even when exposed to an acidic chemical liquid (for example, an acidic plating solution such as a hydrofluoric acid solution or a chromium plating solution, a copper sulfate plating solution, a nickel plating solution, an acidic electroless nickel plating solution, or an acidic tin plating solution used for etching glass). This is advantageous in preventing the acidic chemical liquid from swelling the base material into the protective sheet to prevent the chemical liquid from reaching the adherend (non-treatment target portion). As a preferable base material from the viewpoint of excellent balance between acid resistance and flexibility, a base material comprising a polyolefin resin is exemplified.

The base material may be a single layer or a multilayer structure of two or more layers (for example, a three-layer structure). For example, a multilayered resin film (multilayer film) including the film as described above can be used as a substrate. In the multilayered film, the resin material constituting each layer may be a resin material containing one kind of the above-mentioned resins singly or a resin material in which two or more kinds of resins are blended.

In a preferred form, the substrate is a single-layer or multi-layer polyolefin resin film. Here, the polyolefin resin film refers to a plastic film formed of a resin material containing a polyolefin resin (that is, a resin composed mainly of a polyolefin). The proportion of the polyolefin resin in the resin component (polymer component) in the polyolefin resin film is preferably 50 mass% or more, more preferably 75 mass% or more, and further preferably 90 mass% or more. The resin component may be a film substantially comprising a polyolefin resin. Alternatively, a film formed of a resin material including a resin component (PA, PC, PU, EVA, etc.) other than the polyolefin resin in addition to the polyolefin resin as the main component (for example, a component exceeding 50 mass% .

As the polyolefin resin, one kind of polyolefin may be used alone or two or more kinds of polyolefins may be used in combination. The polyolefin may be, for example, a homopolymer of? -Olefin, a copolymer of two or more? -Olefins, a copolymer of one or more? -Olefins with another vinyl monomer, and the like. Specific examples thereof include ethylene-propylene copolymers such as PE, PP and EPR, ethylene-propylene-butene copolymers, and ethylene-ethyl acrylate copolymers. Both low density (LD) polyolefins and high density (HD) polyolefins are available. As such a polyolefin resin film, a biaxially oriented polypropylene (OPP) film, a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a medium density polyethylene (MDPE) film, a high density polyethylene (HDPE) A polyethylene (PE) film blended with polyethylene (PE), a PP / PE blend film blended with polypropylene (PP) and polyethylene (PE), and various flexible polyolefin films.

The PP may be various polymers (propylene-based polymers) having propylene as the main monomer (main constituent monomer, that is, a component exceeding 50 mass% of the entire monomer). The concept of the propylene polymer as referred to here includes, for example, the following polypropylene.

Homopolymer of propylene (i.e. homopolypropylene). For example, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene.

Random copolymers (random polypropylene) of propylene with other? -Olefins (typically one or more types selected from ethylene and? -Olefins having 4 to 10 carbon atoms). For example, random polypropylene randomly copolymerized with 96 mol% to 99.9 mol% of propylene and 0.1 mol% to 4 mol% of other? -Olefins (preferably ethylene and / or butene).

(Block polypropylene) obtained by block-copolymerizing propylene with another? -Olefin (typically, one or two or more selected from ethylene and? -Olefins having 4 to 10 carbon atoms). The block polypropylene may further comprise a rubber component comprising at least one of propylene and the other? -Olefin as a by-product. For example, a polymer obtained by block-copolymerizing propylene with 90 mol% to 99.9 mol% of another α-olefin (preferably ethylene and / or butene) in an amount of 0.1 mol% to 10 mol%, and propylene and other α- A block polypropylene further comprising a rubber component comprising at least one component.

The polyolefin resin may be a resin (PP resin) in which the main component in the resin component is a propylene polymer as described above and another polymer is blended as a subcomponent. The other polymer is a polyolefin having an alpha -olefin other than propylene, for example, an alpha -olefin having 2 to 4 carbon atoms or 10 to 10 carbon atoms as a main monomer (main constituent monomer, that is, a component exceeding 50 mass% And may be one kind or two or more kinds. The PP resin may be a composition containing at least PE as the subcomponent. The content of PE may be, for example, 3 parts by mass to 50 parts by mass (typically 5 parts by mass to 30 parts by mass) per 100 parts by mass of PP. The resin component may be a PP resin substantially containing PP and PE. Further, a PP resin containing at least PE and EPR as the subcomponent (for example, a PP resin containing PP and PE and EPR as a resin component) may be used. In this case, the EPR content may be 3 parts by mass to 50 parts by mass (typically 5 parts by mass to 30 parts by mass) per 100 parts by mass of PP, for example.

The PE may be a homopolymer of ethylene, or may be a copolymer of ethylene and another? -Olefin (for example, an? -Olefin having 3 to 10 carbon atoms) as a main monomer. Suitable examples of the? -Olefin include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. Low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE) are all available. For example, LDPE and / or LLDPE can be preferably employed.

As the base material, a polyolefin resin film containing an olefinic polymer alloy and a thermoplastic resin containing a carbonyl unit may be used. Here, the carbonyl unit-containing thermoplastic resin means a thermoplastic resin containing a carbonyl (C = O) unit in a molecular skeleton. Such a polyolefin resin film may not substantially contain a halogen atom, and may have flexibility, heat resistance and flame retardancy at the level of polyvinyl chloride (PVC).

The olefinic polymer alloy is mainly a component for suppressing thermal deformation of the base material, and is preferably a polymeric alloy containing an ethylene component and a propylene component. The shape of the polymer alloy is not particularly limited, and for example, a polymer blend in which two or more polymers are physically mixed, a block copolymer or a graft copolymer in which two or more polymers are covalently bonded, and two or more polymers are covalently bonded to each other And IPN (Interpenetrating Polymer Network) structures that are not combined but intertwined with each other. In addition, any of the compatibilizing polymer alloys in which two or more kinds of polymers are compatible and the incompatible polymer alloy in which two or more kinds of polymers are forming a phase separation structure for emergency use may be used.

Examples of such olefinic polymer alloy include polymer blends of polypropylene (homopolypropylene, random polypropylene) and polyethylene (which may be a copolymer of ethylene and a small amount of? -Olefin), propylene / ethylene copolymers, And ternary copolymers of other? -Olefins. Examples of other? -Olefins in the terpolymer include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene. Of these, 1-butene is preferable.

When the olefinic polymer alloy is a copolymer, it is preferably a multistage polymerized olefin copolymer (preferably an ethylene / propylene copolymer) polymerized by two or more stages of multistage polymerization. As such a multi-stage polymerized olefin copolymer, there can be mentioned, for example, polymer alloys as disclosed in Japanese Patent Application Laid-Open No. 2001-192629. That is, the first stage polymerization is carried out by using a monomer mixture containing propylene as a main component, and then the second stage and the following stages are carried out in which a polypropylene (first stage) / propylene-ethylene copolymer Polymer alloy. The first stage polymerization is preferably carried out in the presence of a titanium compound catalyst and an organoaluminum compound catalyst. The polymerization in the second stage and thereafter is preferably carried out in the presence of the titanium-containing polyolefin and the organoaluminum compound catalyst produced in the first stage polymerization. As the titanium compound catalyst, for example, titanium tetrachloride and magnesium chloride are co-milled and treated with n-butyl orthotitanate, 2-ethyl-hexanol, ethyl p-toluate, silicon tetrachloride, diisobutyl phthalate , And spherical solid catalysts having an average particle diameter of 1 to 30 mu m. Examples of the organoaluminum compound catalyst include alkylaluminum such as triethylaluminum. Further, a silicon compound such as diphenyldimethoxysilane may be further added as an electron donor in the polymerization layer. An iodine compound such as ethyl iodide may also be added.

The olefinic polymer alloy preferably exhibits a dynamic storage modulus (E ') of 80 MPa or more and 80 MPa or less (for example, 45 MPa to 160 MPa) at 80 ° C and a dynamic storage modulus E ') of 12 MPa or more and less than 70 MPa (for example, 15 MPa to 65 MPa). Also, in consideration of surface shape compliance and workability in the vicinity of room temperature, the dynamic storage modulus (E ') at 23 캜 is preferably 200 MPa or more and less than 400 MPa. The dynamic elastic modulus (E ') was determined by preparing a test piece (thickness 0.2 mm, width 10 mm, length 20 mm) by using a polymer alloy and measuring the dynamic viscoelastic behavior by temperature dispersion of the test piece by using DMS200 (Seiko Instruments Inc.) (Measurement method: tensile mode, temperature raising rate: 2 DEG C / min, frequency: 1 Hz) using a differential scanning calorimeter. Catalyst KS-353P, Catalyst KS-021P, Catalyst C200F, Catalyst Q-200F and the like, which are available from Sun Allomer Co., Ltd., are examples of such polymer alloys.

The above-mentioned carbonyl unit-containing thermoplastic resin is used for imparting appropriate flexibility and good extensibility to a substrate, and is a thermoplastic resin containing a carbonyl (C = O) unit in a molecular skeleton. When the polyolefin resin film contains an inorganic flame retardant as described later, it may be a component that activates the flame retardancy imparting action by the inorganic flame retardant. As such a thermoplastic resin, a flexible polyolefin-based resin containing a carbonyl unit in a molecular skeleton is suitable. (Ethylene / vinyl ester copolymer, ethylene / unsaturated carboxylic acid copolymer, etc.) synthesized by using a vinyl ester and / or an?,? - unsaturated carboxylic acid or a derivative thereof in a monomer or a comonomer ), Metal salts thereof, and the like. The melting point of such a thermoplastic resin is not particularly limited, but it is preferably 120 占 폚 or lower (typically 40 to 100 占 폚). The melting point can be measured by a general differential scanning calorimeter (DSC).

As the vinyl ester in the ethylenic copolymer or the metal salt thereof, a carboxylic acid vinyl ester such as vinyl acetate is exemplified. Examples of the?,? - unsaturated carboxylic acids or derivatives thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic anhydride and itaconic anhydride, or anhydrides thereof; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl Unsaturated carboxylic acid esters such as lauryl (meth) acrylate, 1-methyl maleate, 1-ethyl maleate, diethyl maleate, 1-methyl fumarate and glycidyl (meth) . These may be used singly or in combination of two or more. Among them, alkyl (meth) acrylate is preferable, and ethyl acrylate is more preferable.

Suitable examples of the ethylene / vinyl ester copolymer and the ethylene / unsaturated carboxylic acid copolymer include ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / ethyl acrylate copolymer, ethylene / acrylic acid / ethyl acrylate copolymer, Ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / ethyl acrylate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / glycidyl methacrylate-ethyl acrylate copolymer and metal salts thereof have. These may be used singly or in combination of two or more.

The polyolefin resin film containing the olefinic polymer alloy and the carbonyl unit-containing thermoplastic resin preferably contains an inorganic flame retardant. Examples of the inorganic flame retardant include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide and barium hydroxide; Basic metal carbonates such as basic magnesium carbonate, magnesium carbonate-calcium carbonate, calcium carbonate, barium carbonate and dolomite; Metal hydrates such as hydrotalcite and borax (hydrates of metal compounds); And inorganic metal compounds such as barium metaborate and magnesium oxide. These may be used singly or in combination of two or more. Among them, metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide and barium hydroxide, and basic magnesium carbonate and hydrotalcite are preferable.

The inorganic flame retardant is also preferably subjected to a surface treatment with a silane coupling agent. As a result, various properties such as flexibility, heat resistance and flame retardancy can be further improved. Specific examples of such silane-based coupling agents include vinyltriethoxysilane, vinyltris (2-methoxy-ethoxy) silane,? -Methacryloxypropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? - Aminopropyltrimethoxysilane, N-phenyl- gamma -aminopropyltrimethoxysilane, N -? - (aminoethyl) -? - aminopropyltrimethoxysilane, N -? - Propyltriethoxysilane, N-phenyl- gamma -aminopropyltriethoxysilane,? - (3,4-epoxycyclohexyl) ethyltrimethoxysilane,? -Glycidoxypropyltrimethoxysilane, Tripropyltrimethoxysilane. These may be used singly or in combination of two or more.

The method of surface treatment of the inorganic metal compound by the silane coupling agent is not particularly limited, and conventionally known methods such as a dry treatment method and a wet treatment method can be suitably adopted. The amount of the silane-based coupling agent to be adhered to the surface of the inorganic metal compound may not be uniformly determined because it may differ depending on the kind of coupling agent, kind of inorganic metal compound, specific surface area, etc. However, To 5.0 parts by mass (for example, 0.3 parts by mass to 3.0 parts by mass).

The blend ratio of the olefinic polymer alloy and the carbonyl unit-containing thermoplastic resin is not particularly limited, but is preferably 90:10 to 20:80 in terms of mass, for example, from the viewpoint of both heat resistance and flame retardancy. When the inorganic flame retardant is blended, the blending amount thereof is preferably in the range of from 100 parts by mass of the polymer component (for example, the total of the multistage polymerized olefin copolymer and the carbonyl unit-containing thermoplastic resin as described above) And more preferably from about 10 parts by mass to about 200 parts by mass (for example, from 20 parts by mass to 100 parts by mass).

Any of the above-mentioned resin films may contain an appropriate component according to the use of the protective sheet, if necessary. Additives such as a light stabilizer such as a radical scavenger and an ultraviolet absorber, an antioxidant, an antistatic agent, a colorant (dye, pigment, etc.), a filler, a slip agent and an anti-blocking agent can be appropriately added. Examples of the light stabilizer include benzotriazoles, hindered amines, benzoates and the like as effective ingredients. Examples of the antioxidant include those containing an alkylphenol, an alkylene bisphenol, a thiopropylene acid ester, an organic phosphoric acid ester, an amine, a hydroquinone, a hydroxylamine and the like as an effective component. Each of these additives may be used alone or in combination of two or more. The amount of the additive to be blended may be about the same as the ordinary blending amount of the resin film used as the base material of the protective sheet in this application depending on the use of the protective sheet (for example, for glass etching and plating masking).

Such a substrate (resin film) can be produced by appropriately adopting conventionally known general film forming methods (extrusion molding, inflation molding, etc.). The surface (the surface on the pressure-sensitive adhesive layer side, the surface to which the pressure-sensitive adhesive is applied) of the side where the pressure-sensitive adhesive layer in the substrate is disposed is subjected to a treatment (a treatment for obtaining an adherence property of the pressure-sensitive adhesive) A surface treatment such as a discharge treatment, an acid treatment, an ultraviolet ray irradiation treatment, a plasma treatment, a primer application, or the like may be carried out. As the surface treatment (primer treatment) by applying the primer coating, it is preferable to use a primer containing an isocyanate in an acrylic polymer. The surface (back surface) opposite to the pressure-sensitive adhesive layer side surface of the substrate may be subjected to surface treatment such as antistatic treatment and peeling treatment as necessary. As the peeling treatment, for example, by forming a long-chain alkyl-based or silicon-based peeling treatment layer on the back surface of the base material, the rewinding force of the protective sheet wound in a roll shape can be lightened.

The thickness of the substrate can be appropriately selected depending on the flexibility (hardness) of the resin film to be used and the like. The thickness of the substrate is usually 500 占 퐉 or less (preferably 300 占 퐉 or less, more preferably 200 占 퐉 or less, typically 100 占 퐉 or less, for example, 80 占 퐉 or less from the viewpoint of followability and adhesion to the stepped surface) ) Is appropriate. The thickness of the base material is preferably 10 占 퐉 or more (preferably 20 占 퐉 or more, more preferably 25 占 퐉 or more, for example, 30 占 퐉 or more) from the viewpoints of peelability and other handling properties (handling property). When the thickness of the substrate is increased, swelling intrusion of the chemical liquid from the surface of the protective sheet tends to be easily prevented.

The kind of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer disposed on the substrate is not particularly limited. For example, one kind or two or more kinds selected from various known pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives (natural rubber-based, synthetic rubber-based compounds, etc.), silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyether pressure- It may be an adhesive. Among them, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive are preferable from the viewpoint of excellent resistance to a chemical liquid (for example, an acidic chemical liquid such as an etching solution or an acidic plating solution). Similarly, the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive is not particularly limited, and a polymer constituting the above-mentioned pressure-sensitive adhesive may be blended and a compounding ratio thereof appropriately selected may be used.

Among them, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is preferably an acrylic pressure-sensitive adhesive containing an acrylic polymer as the base polymer. Here, the term " base polymer " refers to a main component (main adhesive component) in the polymer component contained in the pressure-sensitive adhesive, and typically refers to a component occupying more than 50 mass% of the polymer component. Further, the "acrylic polymer" refers to a polymer comprising monomer units derived from a monomer (acrylic monomer) having at least one (meth) acryloyl group in one molecule. The acrylic polymer may include a monomer raw material (a single monomer or a monomer mixture) which may further contain an acrylic monomer and another monomer having a copolymerization with the acrylic monomer (i.e., a monomer having no (meth) acryloyl group) Or may be a polymer (copolymer) synthesized by polymerization.

As a typical example of the acrylic polymer, the main component of the acrylic monomer contained in the monomer raw material is alkyl (meth) acrylate. The term " (meth) acrylate " refers to both acrylate and methacrylate. Likewise, " (meth) acryloyl " means acryloyl and methacryloyl, and " (meth) acryloyl "

The proportion of the alkyl (meth) acrylate in the acrylic monomer contained in the monomer raw material is typically more than 50% by mass, preferably 60% by mass or more, and more preferably 70% by mass or more, May be 80% by mass or more. In a preferred form, the proportion of alkyl (meth) acrylate in the acrylic monomers may be at least 90 mass%. As the acrylic monomer, a monomer raw material having a composition containing only alkyl (meth) acrylate may be used. Alternatively, the monomer raw material may include an acrylic monomer other than alkyl (meth) acrylate, for example, for adjusting the adhesive property or the gel fraction. In this case, the proportion of the alkyl (meth) acrylate in the acrylic monomer in the monomer raw material may be, for example, 99.5 mass% or less and 99 mass% or less (for example, 98 mass% or less).

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be appropriately used.

CH ₂ = CR ¹ COOR ² (1)

Here, R ¹ in the formula (1) is a hydrogen atom or a methyl group. R ² is a linear or branched alkyl group, typically a C _1-20 alkyl group. (Meth) acrylate in which R ² is an alkyl group of C _1-14 (for example, C _1-10 ) from the viewpoint of the storage modulus of the pressure-sensitive adhesive and the like.

In the present specification, C _ab refers to the range of the number of carbon atoms (a or more and b or less). For example, the C _1-20 alkyl group refers to an alkyl group having 1 to 20 carbon atoms.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl Butyl (meth) acrylate, isobutyl (meth) acrylate, isobutyl (meth) acrylate, isobutyl (Meth) acrylate, octyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl Pentadecyl (meth) acrylate, hexadecyl ( (Meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate and eicosyl (meth) acrylate. These may be used singly or in combination of two or more.

Among them, alkyl (meth) acrylates in which R ² is a C _4-10 alkyl group such as n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate are preferred. For example, one or more of these may be used in a total amount of 30 mass% or more (preferably 40 mass% or more and 99 mass% or less, for example, 50 mass% or more and 98 mass% or less, typically 50 mass% By mass to 97% by mass or less). (Meth) acrylate in which R ² is a C _4-10 alkyl group is contained in an amount of 40 mass% or more and 90 mass% or less (more preferably 50 mass% or more and 80 mass% or less , Typically 50% by mass or more and 70% by mass or less, for example, 50% by mass or more and 60% by mass or less).

In a preferred form of the technique disclosed in the present specification, monomers in which R ² in the formula (1) is an alkyl group having 6 or more carbon atoms (for example, 7 or more, typically 8) can be used. Such a monomer has a high hydrophobicity because the number of carbon atoms of the alkyl group is relatively large, and thus the effect of preventing the entry of a chemical liquid (particularly, a chemical liquid containing an aqueous solvent) can be expected. The number of the carbon atoms is preferably set to about 20 or less in consideration of the availability of raw materials, ease of production, polymerization reactivity, and ability to prevent chemical solution penetration. For example, alkyl (meth) acrylates wherein R ² is a hexyl group, heptyl group, octyl group, nonyl group, 2-ethylhexyl group, propylhexyl group and the like are preferable. Of these, alkyl (meth) acrylates in which R ² is a 2-ethylhexyl group can be mentioned as preferred monomers. These monomers may be used singly or in combination of two or more.

In this embodiment, when a monomer in which R ² in the formula (1) is an alkyl group having 6 or more carbon atoms (for example, 7 or more, typically 8) is used, the monomer raw material has a glass transition temperature (Tg) (Meth) acrylate in which R ² in the formula (1) is an alkyl group of C _1-5 , for the purpose of adjustment or cohesion. Examples of such alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (Meth) acrylate, isobutyl (meth) acrylate, isobutyl (meth) acrylate, isobutyl (meth) acrylate and the like. These may be used singly or in combination of two or more.

Among the alkyl (meth) acrylates represented by the above formula (1), the proportion of monomers in which R ² is an alkyl group having 6 or more carbon atoms can be, for example, in a proportion exceeding 50 mass%, preferably 60 mass % Or more, and more preferably 70 mass% or more. From the viewpoint of enhancing the hydrophobicity of the obtained pressure-sensitive adhesive and enhancing the ability of the pressure-sensitive adhesive to penetrate (typically, the ability to prevent the penetration of a chemical liquid mainly due to the swelling of the pressure-sensitive adhesive in the aqueous medium) 90 mass% or more, typically 95 mass% or more). As the alkyl (meth) acrylate, only monomers in which R ² is an alkyl group having 6 or more carbon atoms may be used. Accordingly, the proportion of the alkyl (meth) acrylate having an alkyl group of 1 to 5 carbon atoms in the alkyl (meth) acrylate represented by the above formula (1) is 20 mass% or less (for example, 10 mass% And typically not more than 5% by mass). Or an alkyl (meth) acrylate in which R ² is an alkyl group of C _1-5 .

The monomer raw material used for synthesizing the acrylic polymer may be a comonomer copolymerizable with alkyl (meth) acrylate other than alkyl (meth) acrylate (hereinafter also referred to as monomer A) , Or monomer B). Such a comonomer can be used for the purpose of improving properties such as adhesion, non-staining (adhesive residual property), light fastness, heat resistance and the like. The monomer B is not limited to a monomer but may be an oligomer copolymerizable with the monomer A.

Examples of the monomer B include a monomer having a functional group (hereinafter, also referred to as a functional group-containing monomer). These functional group-containing monomers can be added for the purpose of introducing crosslinking points into the acrylic polymer and enhancing cohesion of the acrylic polymer. As such a functional group-containing monomer,

For example, ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, carboxyethyl (meth) acrylate and carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and citraconic acid Carboxyl group-containing monomers such as ethylenically unsaturated dicarboxylic acid;

Acid anhydride group-containing monomers such as acid anhydrides such as ethylenically unsaturated dicarboxylic acids such as maleic anhydride and itaconic anhydride;

(Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Hydroxyethyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (Meth) acrylates such as N-methylol (meth) acrylate, vinyl alcohol, allyl alcohol, 2-hydroxy (meth) Hydroxyl group-containing monomers such as unsaturated alcohols such as ethyl vinyl ether, 4-hydroxybutyl vinyl ether and diethylene glycol monovinyl ether;

The functional group-containing monomers containing a nitrogen atom in the functional group, such as the amide group-containing monomer, the amino group-containing monomer and the cyano group-containing monomer,

(Meth) acrylamide, N-methylol (meth) acrylamide, N-methylol (meth) acrylamide, Amide group-containing monomers such as N-methoxymethyl (meth) acrylamide and N-butoxymethyl (meth) acrylamide;

Amino group-containing monomers such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate and t-butylaminoethyl (meth) acrylate;

For example, cyano group-containing monomers such as acrylonitrile and methacrylonitrile;

(Meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalenesulfonic acid. Sulfonic acid group-containing monomers;

For example, a phosphoric acid group-containing monomer such as 2-hydroxyethyl acryloyl phosphate;

For example, an epoxy group (glycidyl group) -containing monomer such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether;

Examples thereof include keto-containing monomers such as diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate and vinyl acetoacetate;

Isocyanate group-containing monomers such as, for example, 2- (meth) acryloyloxyethyl isocyanate;

For example, alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate;

(Meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, Alkoxysilyl group-containing monomers such as methyldiethoxysilane;

. These may be used singly or in combination of two or more. Among them, functional group-containing monomers such as a carboxyl group, a hydroxyl group and an epoxy group are preferable from the viewpoint that a crosslinking point can be appropriately introduced into the acrylic polymer and the cohesive force of the acrylic polymer can be further increased. More preferred are a carboxyl group-containing monomer or a hydroxyl group-containing monomer. Particularly preferred are carboxyl group-containing monomers.

The monomer raw material in the techniques disclosed in this specification may contain monomers other than the functional group-containing monomers as the monomer B for the purpose of adjusting the Tg of the acrylic polymer or improving cohesion. Examples of such monomers include carboxylic acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate and vinyl benzoate;

Aromatic vinyl compounds such as styrene, substituted styrene (? -Methylstyrene and the like) and vinyltoluene;

(Meth) acrylates, such as aryl (meth) acrylates (e.g., phenyl (meth) acrylate), aryloxyalkyl (meth) (Meth) acrylate); aromatic ring-containing (meth) acrylates such as benzyl (meth) acrylate;

Vinyl pyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N Monomers having nitrogen atom-containing rings such as vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam and N- (meth) acryloylmorpholine;

For example, olefinic monomers such as ethylene, propylene, isoprene, butadiene and isobutylene;

Chlorine-containing monomers such as vinyl chloride and vinylidene chloride;

Vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether;

(Meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and the like. These may be used singly or in combination of two or more.

The monomer raw material may further contain a comonomer such as a polyfunctional monomer for crosslinking or the like as monomer B, if necessary. Examples of such a polyfunctional monomer include hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, Methacrylate, and the like. These may be used singly or in combination of two or more.

The total amount of such acrylic monomers (monomers having at least one (meth) acryloyl group in one molecule) may be, for example, 30 mass% or more of the total monomer raw materials constituting the acrylic polymer. The total amount of the acrylic monomers is preferably 40% by mass or more, more preferably 50% by mass or more (for example, 50% by mass or more) of the total monomer raw materials constituting the acrylic polymer from the viewpoints of adhesion to the adherend Do. In one form, the total amount of the acrylic monomers is preferably at least 70 mass% (preferably at least 80 mass%, more preferably at least 90 mass%, such as at least 95 mass%, more preferably at least 95 mass%) of the entire monomer raw material constituting the acrylic polymer May be 99 mass% or more), or may be a monomer raw material containing only an acrylic monomer.

The acrylic polymer may also be a copolymer of an acrylic monomer and a monomer other than an acrylic monomer. In this case, the copolymerization ratio of the monomers other than the acrylic monomers may be, for example, 1 to 70 mass%, usually 1 to 60 mass%, preferably 5 to 50 mass%, and preferably 10 to 50 mass% Is more preferable. In a preferred form, the copolymerization ratio of the monomers other than the acrylic monomer may be 20 to 50 mass% (for example, 30 mass% or more and less than 50 mass%).

When the above-mentioned functional group-containing monomer is used as the monomer constituting the acrylic polymer, it is preferable to use an alkyl (meth) acrylate (preferably, R ² in the formula (1) functional group-containing monomer based on 100 parts by mass of an alkyl group of C _4-10 alkyl (meth) acrylate) (preferably a carboxyl group-containing monomer) to 1 part by mass to 10 parts by mass (for example, 2 parts by mass to 8 parts by weight , Typically 3 parts by mass to 7 parts by mass). For example, the use of an appropriate amount of a carboxyl group-containing monomer improves the adhesion to an adherend (particularly an adherend having a surface including a glass or other polar material) and prevents the penetration of a drug solution from the interface between the adherend and the adherend Can be prevented more effectively.

When monomers other than the above-mentioned functional group-containing monomer are used as the monomers constituting the acrylic polymer, alkyl (meth) acrylates (preferably, R ² in the formula (1) (Preferably an alkyl (meth) acrylate wherein the alkyl group is a C _4-10 alkyl group) in an amount of 1 part by mass to 100 parts by mass For example, 2 parts by mass to 90 parts by mass, typically 5 parts by mass to 85 parts by mass).

When the above-mentioned polyfunctional monomer is used as a monomer constituting the acrylic polymer, it is preferable to use an alkyl (meth) acrylate (preferably, R ² in the formula (1) is a C alkyl group of the alkyl (meth) acrylates of _{4 to 10)} or less with respect to 100 parts by mass 30 parts by mass of the polyfunctional monomer (for example, 20 parts by mass or less, which is typically a unit comprising 1 to 10 parts by weight by weight) desirable.

In one preferred form of the techniques disclosed herein, the acrylic polymer may comprise an alkyl (meth) acrylate and a carboxylic acid vinyl ester in its monomer composition. Such an acrylic polymer is typically obtained by polymerizing (typically, solution polymerization) a monomer raw material comprising an alkyl (meth) acrylate and a carboxylic acid vinyl ester. The use of the carboxylic acid vinyl ester can contribute to prevention of the penetration of the chemical liquid from the interface between the pressure-sensitive adhesive and the adherend by improving the adhesion with the adherend (for example, a glass substrate).

Examples of the carboxylic acid vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate, vinyl benzoate and the like. These may be used singly or in combination of two or more. Among them, from the viewpoint of improving low-speed peel strength, a homopolymer such as vinyl acetate, vinyl propionate or vinyl butyrate has a glass transition temperature (Tg) higher than -20 ° C (for example, higher than -20 ° C and lower than or equal to 80 ° C) Acid vinyl esters are preferred. Particularly preferred carboxylic acid vinyl esters include vinyl acetate.

The content ratio of the carboxylic acid vinyl ester in the monomer raw material (when the two or more kinds of carboxylic acid vinyl esters are included, the total content thereof) may be, for example, 1 to 60% by mass, and preferably 5 to 50% %, More preferably from 10 to 50 mass%. In a preferred form, the content ratio of the carboxylic acid vinyl ester may be 20 to 50 mass% (for example, 30 mass% or more and less than 50 mass%).

The technique disclosed in this specification can be preferably implemented in a form in which the monomer raw material constituting the acrylic polymer is a composition containing only an alkyl (meth) acrylate and a carboxyl group-containing monomer as acrylic monomers. One suitable example of this type is a form containing only an alkyl (meth) acrylate and a carboxyl group-containing monomer as an acrylic monomer and a vinyl carboxylate ester (for example, vinyl acetate) as a monomer other than an acrylic monomer . In this case, it is preferable to include about 15 to 100 parts by mass (for example, 30 to 95 parts by mass, typically 50 to 90 parts by mass) of the carboxylic acid vinyl ester with respect to 100 parts by mass of the alkyl (meth) acrylate .

Although not particularly limited, the copolymer composition of the acrylic polymer is preferably set so that the Tg of the acrylic polymer is in the range of -70 占 폚 to -20 占 폚. The Tg of the acrylic polymer is preferably from -60 deg. C to -20 deg. C (more preferably, from -50 deg. C to -20 deg. C, for example, from -40 deg. C to -20 deg. C ) Is more preferable. When the Tg of the acrylic polymer is not too high, good adhesion to the surface of the adherend is exhibited, and the penetration of the drug solution from the interface between the pressure sensitive adhesive and the adherend can be effectively prevented. In addition, the Tg of the acrylic polymer not too low also contributes to prevention of the penetration of the liquid medicament (typically, the penetration of the liquid medicament mainly due to the swelling of the pressure sensitive adhesive by the liquid medicament).

Here, the Tg of the acrylic polymer is a value obtained from the Fox equation based on the Tg of the homopolymer (homopolymer) of each monomer constituting the polymer and the mass fraction (copolymerization ratio on the mass basis) of the monomer It says. Therefore, the Tg of the acrylic polymer can be adjusted by appropriately changing the composition of the monomer raw material (that is, the ratio of the type and amount of the monomer used for synthesizing the polymer). As the Tg of the homopolymer, the values described in the known data shall be adopted.

In the techniques disclosed in this specification, the following values are specifically used as the Tg of the homopolymer.

2-ethylhexyl acrylate-70 < 0 > C

n-Butyl acrylate -55 占 폚

Ethyl acrylate -22 ° C

Methyl acrylate 8 ° C

Methyl methacrylate 105 ° C

Cyclohexyl methacrylate 66 ° C

Vinyl acetate 32 ° C

2-hydroxyethyl acrylate-15 C

Styrene 100 ℃

Vinyl chloride 82 ° C

Acrylic acid 106 ° C

Methacrylic acid 228 ° C

For the Tg of the homopolymer other than those exemplified above, the numerical values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) are used.

In the case where it is not described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc, 1989), the value obtained by the following measuring method is used (see Japanese Patent Application Laid-Open No. 2007-51271 ).

Specifically, 100 parts by mass of a monomer, 0.2 parts by mass of azobisisobutyronitrile and 200 parts by mass of ethyl acetate as a polymerization solvent were fed into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser, Stir for 1 hour. After the oxygen in the polymerization system was removed in this way, the temperature was raised to 63 캜 and the reaction was carried out for 10 hours. Subsequently, the solution was cooled to room temperature to obtain a homopolymer solution having a solid concentration of 33% by weight. Subsequently, this homopolymer solution is coated on the release liner in a flexible manner and dried to produce a test sample (sheet-like homopolymer) having a thickness of about 2 mm. This test sample was punched into a disc shape having a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to shear strain at a frequency of 1 Hz using a viscoelasticity tester (ARES, manufactured by Rheometrics Co.) The viscoelasticity is measured by a shearing mode at a heating rate of 占 폚 / minute, and the peak top temperature of tan? Is defined as Tg of the homopolymer.

The method of polymerizing the monomer or a mixture thereof (monomer raw material) is not particularly limited, and conventionally known general polymerization methods can be adopted. Examples of such polymerization methods include solution polymerization, emulsion polymerization, bulk polymerization and suspension polymerization. Among them, solution polymerization is preferable because of its excellent water resistance and chemical solution penetration prevention property. The form of polymerization is not particularly limited, and can be carried out by appropriately selecting conventionally known monomer feeding methods, polymerization conditions (temperature, time, pressure, etc.), and components other than monomers (polymerization initiator, polymerization solvent and the like). For example, as the monomer supplying method, the entire monomer mixture may be supplied (batch supply) to the reaction vessel at a time, may be gradually supplied dropwise (continuous supply), divided into several batches, Supply). The monomer or a mixture thereof may be supplied as a solution in which a part or the whole is dissolved in a solvent or as a dispersion in which it is emulsified in water.

When the emulsion polymerization is adopted as the polymerization method of the acrylic polymer, an emulsifier for general emulsion polymerization may be suitably selected and used as an emulsifier (surfactant). It is usually preferable to use an anionic emulsifier or a nonionic emulsifier (a radically polymerizable emulsifier having a radical polymerizable functional group (reactive emulsifier)). These emulsifiers may be used singly or in combination of two or more kinds. The amount of the emulsifier to be used (based on the solid content) may be, for example, about 0.2 to 10 parts by mass (preferably about 0.5 to 5 parts by mass) relative to 100 parts by mass of the monomer raw material.

When solution polymerization is adopted as the polymerization method of the acrylic polymer, examples of the polymerization solvent include aromatic compounds (typically, aromatic hydrocarbons) such as toluene and xylene; Acetic acid esters such as ethyl acetate and butyl acetate; Aliphatic or alicyclic hydrocarbons such as hexane, cyclohexane, and methylcyclohexane; Halogenated alkanes such as 1,2-dichloroethane and 1,2-dichloroethane; Ketones such as methyl ethyl ketone and acetyl acetone; Or a mixed solvent of two or more kinds can be used.

Examples of the polymerization initiator include, but are not limited to, an azo-based initiator, a peroxide-based initiator, a substituted ethane-based initiator, and a redox initiator in combination with an oxidizing agent such as peroxide and a reducing agent. Examples of the azo initiator include 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, Azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2,2'-azobis (2-methylpropionamidine) , 2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) Dihydrochloride is exemplified. Examples of the peroxide initiator include persulfates such as potassium persulfate and ammonium persulfate; Benzoyl peroxide (BPO), t-butyl hydroperoxide, and hydrogen peroxide. As the substituted ethane-based initiator, for example, phenyl-substituted ethane is exemplified. Examples of the redox initiator include a combination of persulfate and sodium hydrogen sulfite, and a combination of peroxide and sodium ascorbate. Among them, an azo-based initiator is preferable from the viewpoint of preventing the penetration of a liquid medicament.

The amount of the polymerization initiator to be used may be appropriately selected according to the kind of the polymerization initiator, the kind of the monomer (composition of the monomer mixture), and the like. Usually, the amount is selected from the range of about 0.005 mass part to 1 mass part per 100 mass parts of the monomer raw material . As the method of supplying the polymerization initiator, all of the batch injection method, the continuous feed method, the divided feed method, etc. in which substantially all of the polymerization initiator to be used is put into the reaction vessel before the supply of the monomer mixture is started can be adopted. From the standpoint of ease of polymerization operation, ease of process control, and the like, for example, a batch injection system can be preferably employed. The polymerization temperature may be, for example, about 20 캜 to 100 캜 (typically 40 캜 to 90 캜).

In the polymerization, various conventionally known chain transfer agents (which may also be regarded as molecular weight regulators or polymerization degree regulators) may be used, if necessary. Such chain transfer agents include, for example, dodecylmercaptan (dodecanethiol), glycidylmercaptan, 2-mercaptoethanol, mercaptoacetic acid, 2-ethylhexyl thioglycolate, 2,3- dimercapto- , And the like. When a chain transfer agent is used, the amount to be used is not particularly limited, but may be about 0.001 to 0.5 parts by mass based on 100 parts by mass of the monomer raw material. Alternatively, a chain transfer agent may not be used. As a preferred form, there is a form in which the monomer raw material is polymerized by solution polymerization without using a chain transfer agent.

The weight-average molecular weight of the acrylic polymer is not particularly limited, but usually it is suitably about 30 × 10 ⁴ to 150 × 10 ⁴ . When using a solution polymerization as a polymerization method, the solution viscosity or the weight average molecular weight of the acrylic polymer from the standpoint of adhesive performance, the 30 × 10 ⁴ to 70 × 10 ⁴ about the degree suitable and, 40 × 10 ⁴ to 60 × 10 ⁴ desirable.

The pressure-sensitive adhesive layer of the protective sheet disclosed in this specification may be formed using a pressure-sensitive adhesive composition comprising an acrylic polymer as described above. The pressure-sensitive adhesive composition may be prepared, for example, by adding appropriate treatments such as concentration adjustment and pH adjustment to the polymerization reaction liquid obtained by polymerizing the monomer raw material (typically solution polymerization) or by adding a pressure- A tackifier, etc.) and an additive (for example, a cross-linking agent).

The form of the pressure-sensitive adhesive composition is not particularly limited. For example, various forms such as a solvent type, an aqueous emulsion type, an aqueous solution type, an active energy ray (e.g., ultraviolet ray) curable type, a hot melt type and the like. Among them, a solvent-type pressure-sensitive adhesive composition is particularly preferable from the viewpoint of resistance to aqueous chemical liquids (chemical solution penetration resistance). Such a solvent-type pressure-sensitive adhesive composition is typically prepared in the form of a solution containing the acrylic polymer in an organic solvent. As the organic solvent, the same polymerization solvent as used for solution polymerization can be used. Although it is not particularly limited, it is generally preferable to prepare the above solvent-type pressure-sensitive adhesive composition from 10 to 55 mass% (for example, from 15 to 45 mass%) of solid content (NV) from the viewpoints of drying efficiency of the pressure- It is suitable.

The pressure-sensitive adhesive composition (typically, a solvent-type pressure-sensitive adhesive composition) in the techniques disclosed in this specification preferably includes a release-controlling agent in addition to the acrylic polymer. As the peeling adjustment agent, various materials capable of adjusting the balance (low P _L / P _H ) between the low peeling strength (P _L ) and the high peeling strength (P _H ) can be used. Particularly, it is preferable to use a peeling adjustment agent capable of raising the value of P _L / P _H by significantly lowering the high-speed peeling strength as compared with the low-speed peeling strength.

The technique disclosed in this specification can be preferably carried out in a form including a compound having a hydrophilic portion and an oleophilic portion in one molecule as the peel adjustment agent. As the peeling adjustment agent, known anionic surfactants, nonionic surfactants, cationic surfactants and the like can be used. Of these, anionic surfactants or nonionic surfactants are preferred.

Examples of the anionic surfactant include alkylbenzenesulfonic acid salts such as sodium dodecylbenzenesulfonate; Alkylsulfuric acid salts such as sodium laurylsulfate and ammonium laurylsulfate; (Poly) ether amines such as (poly) oxyethylene laurylamine and (poly) oxyethylene stearylamine; (Poly) ether sulfates such as (poly) oxyethylene alkyl ether sulfates, (poly) oxyethylene alkyl phenyl ether sulfates, and (poly) oxyethylene alkyl phenyl ether sulfates; (Poly) oxyethylene alkylsulfosuccinate, and (poly) oxyethylene alkyl ether phosphate esters.

Examples of the nonionic surfactant include (poly) oxyethylene alkyl ether, (poly) oxyethylene alkyl phenyl ether, (poly) oxyethylene fatty acid ester and polyoxyethylene polyoxypropylene block polymer.

Here, (poly) oxyethylene means both the number of repeating oxyethylene units (the number of added moles of ethylene oxide) and the number of repeating units of two or more. The same applies to (poly) ether.

In one preferred form of the technique disclosed in this specification, the peeling adjustment agent has at least one of -POH group, -COH group and -SOH group. Among them, a peel adjustment agent having a -POH group is preferable. Such a release modifier typically comprises a phosphate ester structure, for example a monoester of phosphoric acid (ROP (= O) (OH) ₂ wherein R is a monovalent organic), diester ((RO) ₂ P (= O) OH wherein R may be the same or different monovalent organic groups), a mixture comprising both monoesters and diesters, and the like.

Examples of the peeling agent having a -POH group include phosphoric acid alkyl esters and (poly) oxyethylene alkyl ether phosphoric acid esters. The (poly) oxyethylene alkyl ether phosphate ester as the peeling adjustment agent may be a monoester of phosphoric acid, a diester, or a mixture containing both a monoester and a diester.

The average number of repeating oxyethylene units in the (poly) oxyethylene alkyl ether phosphate ester may be, for example, about 1 to 10. (Poly) oxyethylene alkyl ether phosphate ester having an average repetition number of 1 to 6 (for example, 2 to 4) in view of the balance between the ability to lower the high-speed peel strength and the prevention of the penetration of the chemical solution.

The alkyl group in the (poly) oxyethylene alkyl ether phosphate ester may be, for example, an alkyl group having 6 to 20 carbon atoms. The number of carbon atoms of the alkyl group is preferably from 8 to 20, more preferably from 10 to 20, and still more preferably from 12 to 20 (typically, from the viewpoint of balance between the ability to lower the high- 13 to 20, for example 16 to 18).

As a commercially available product of (poly) oxyethylene alkyl ether phosphate ester which can be preferably used as a release-modifying agent in the art disclosed in the present specification, "Fospanol (registered trademark)" series manufactured by Tohoku Kagaku Kogyo Co., . Specific examples include phospholipids such as phosphanol RL-210, phosphanol RL-310, phosphanol RM-410, phosphanol RS-410, phosphanol ED-200, phosphanol ML-220 and phosphanol ML- .

Another suitable example of the peel adjustment agent is (poly) ether amine. For example, a (poly) etheramine represented by the following formula (2) can be used.

R ³ -N [- (CH ₂ CH ₂ O) _n -H] ₂ (2)

Here, n in the formula (2) is 1 to 20, typically 1 to 10. R ³ is a hydrocarbon group and is, for example, a C _10-30 saturated or unsaturated hydrocarbon group, preferably a C _10-20 (more preferably C _14-18 ) alkyl group. Suitable examples of the compound represented by the formula (2) include (poly) oxyethylene laurylamine and (poly) oxyethylene stearylamine. Among them, (poly) oxyethylene stearylamine is preferable.

Although not particularly limited, those having a HLB (Hydrophile-Lipophile Balance) value of about 4 to 15 (more preferably about 5 to 10) can be preferably used as the release control agent in the techniques disclosed in this specification.

The molecular weight of the peel adjustment agent is not particularly limited. From the standpoint of appropriately exerting the effect of containing the release-modifying agent (that is, the effect of adjusting the value of P _L / P _H , particularly the effect of lowering the P _H intensively) and also suppressing the deterioration of the pressure- Usually, a release control agent having a molecular weight (mass average molecular weight in the case of distribution in molecular weight) of about 200 to 5000 (for example, about 300 to 3000) is preferable.

In the techniques disclosed in this specification, the peeling adjustment agent may be used alone or in combination of two or more. As a peeling adjustment agent according to a preferred form, a peeling adjustment agent containing only one or two or more (poly) oxyethylene alkyl ether phosphate esters is exemplified. As a peeling adjustment agent according to another preferred embodiment, a peeling adjustment agent comprising a combination of a peeling adjustment agent having -POH group and (poly) etheramine is exemplified. For example, a peel adjustment agent comprising a combination of a (poly) oxyethylene alkyl ether phosphate ester and the (poly) ether amine represented by the formula (2).

The amount of the peeling adjustment agent to be used can be set so that the values of P _H and P _L / P _H of the protective sheet are in the preferred ranges disclosed in this specification. The content of the peeling agent in 100 parts by mass of the acrylic polymer may be, for example, 0.01 to 15 parts by mass. From the viewpoint of appropriately exhibiting the effect of containing the release-modifying agent and suppressing the deterioration of the adhesion property, the content of the release-controlling agent (when the two or more kinds of release-regulating agents are used, the total content thereof) It is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass.

When the (poly) oxyethylene alkyl ether phosphate ester is used as the peeling adjustment agent, the content of the (poly) oxyethylene alkyl ether phosphate ester relative to 100 parts by mass of the acrylic polymer may be, for example, 0.01 to 5 parts by mass, 0.05 to 3 parts by mass, and more preferably 0.1 to 2 parts by mass.

When (poly) etheramine is used as the peeling agent, the content of (poly) etheramine in 100 parts by mass of the acrylic polymer may be, for example, 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass .

When the (poly) oxyethylene alkyl ether phosphate ester and the (poly) ether amine are used in combination as the peeling adjustment agent, the mass ratio of the (poly) oxyethylene alkyl ether phosphate ester to the (poly) ether amine is not particularly limited, / 5 to 5/1, and more preferably 1/3 to 3/1 (more preferably 1/1 to 1/3).

The pressure-sensitive adhesive composition preferably includes a crosslinking agent. The kind of the crosslinking agent is not particularly limited and may be suitably selected from various crosslinking agents commonly used in the pressure sensitive adhesive field, for example, depending on the kind of the crosslinkable functional group of the functional group-containing monomer. Examples of the various crosslinking agents usually used in the pressure sensitive adhesive field include isocyanate crosslinking agents such as polyisocyanate, silane crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, metal chelating crosslinking agents and melamine crosslinking agents. These crosslinking agents may be used singly or in combination of two or more.

Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate; Alicyclic isocyanates such as isophorone diisocyanate; Aliphatic isocyanates such as hexamethylene diisocyanate; And the like. More specifically, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; Cycloaliphatic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; Aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; Trimethylolpropane / tolylene diisocyanate trimer adduct (trade name: Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (trade name: Coronate HL , An isocyanate adduct of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name " Coronate HX "); And the like. As the isocyanate-based crosslinking agent, one of these isocyanate compounds may be used alone or two or more of them may be used in combination.

Examples of the epoxy crosslinking agent include N, N, N ', N'-tetraglycidyl-m-xylenediamine (trade name "TETRAD-X", available from Mitsubishi Gas Chemical Co., Glycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name " TETRAD-C "). Examples of the melamine-based crosslinking agent include hexamethylol melamine and the like.

Of these, isocyanate-based crosslinking agents can be mentioned as preferred crosslinking agents. The technique disclosed in the present specification uses a crosslinking agent that contains an isocyanate crosslinking agent and does not contain an epoxy crosslinking agent (typically, a crosslinking agent containing only an isocyanate crosslinking agent) from the viewpoint of highly compatibility between the liquid penetration prevention and the peeling workability Or the like. The use of the isocyanate-based crosslinking agent is also advantageous from the viewpoint that it is easy to control the gel fraction of the pressure-sensitive adhesive described below to the preferable range disclosed in this specification.

The pressure-sensitive adhesive composition according to a preferred embodiment includes a combination of an acrylic polymer with a carboxyl group-containing monomer as a functional group-containing monomer and a cross-linking agent (which may be a crosslinking agent containing only an isocyanate-based cross-linking agent) including an isocyanate-based cross-linking agent. With such a pressure-sensitive adhesive composition, it is possible to realize a protective sheet which is highly compatible with the adhesiveness and peeling workability. It is also advantageous from the viewpoint that it is easy to control the gel fraction of the pressure-sensitive adhesive to the preferable range disclosed in this specification. From the viewpoints of ease of control of the gel fraction and adhesion to an adherend, the techniques disclosed in this specification are preferably used in a form in which the carboxyl group-containing monomer is copolymerized with the acrylic polymer and the hydroxyl group-containing monomer is not substantially copolymerized . A combination of such an acrylic polymer and a crosslinking agent comprising an isocyanate crosslinking agent (typically a crosslinking agent containing only an isocyanate crosslinking agent) is particularly preferable.

The amount of the cross-linking agent contained in the pressure-sensitive adhesive composition is not particularly limited, but it is generally from 0.5 to 10 parts by mass (for example, from 1 to 7 parts by mass, preferably from 1 to 7 parts by mass) based on 100 parts by mass of the acrylic polymer from the viewpoints of both adhesion and peeling workability. , Typically 2 to 7 parts by mass).

The pressure-sensitive adhesive composition may further include a crosslinking accelerator. The type of the crosslinking accelerator may be appropriately selected depending on the kind of the crosslinking agent to be used. In the present specification, the term "crosslinking accelerator" refers to a catalyst that increases the rate of crosslinking reaction by a crosslinking agent. Examples of such cross-linking accelerators include tin such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tetra-n-butyltin and trimethyltin hydroxide (Sn) -containing compound; Nitrogen (N) -containing compounds such as amines such as N, N, N ', N'-tetramethylhexanediamine and triethylamine, and imidazoles. Among them, a Sn-containing compound is preferable. The amount of the crosslinking accelerator included in the pressure-sensitive adhesive composition may be, for example, about 0.001 mass part to 0.5 mass part (preferably about 0.001 mass part to 0.1 mass part) relative to 100 mass parts of the acrylic polymer. Further, the technique disclosed in this specification can be preferably implemented in a form in which the pressure-sensitive adhesive composition does not substantially contain a crosslinking accelerator in consideration of easiness in controlling the gel fraction of the pressure-sensitive adhesive, adhesion to the adherend, and the like.

The pressure-sensitive adhesive composition may contain a tackifier if necessary. As the tackifier, conventionally known ones can be used without particular limitation. Examples of the thermoplastic resin include a terpene type tackifying resin, a phenolic tackifying resin, a rosin type tackifying resin, an aliphatic petroleum resin, an aromatic petroleum resin, a copolymer petroleum resin, an alicyclic petroleum resin, a xylene resin, A polyamide-based tackifying resin, a ketone-based tackifying resin, and an elastomer-based tackifying resin. These may be used singly or in combination of two or more. When the tackifier is used, the amount of the tackifier is preferably not more than 50 parts by mass (typically, from 0.1 part by mass to 30 parts by mass) based on 100 parts by mass of the acrylic polymer from the viewpoint of sufficiently obtaining the effect of the tackifier without deteriorating the properties of the acrylic polymer Part) is preferable. Further, the technique disclosed in this specification can be preferably implemented in a form in which the pressure-sensitive adhesive composition contains substantially no tackifier in view of the adhesion property and the residual adhesive property of the pressure-sensitive adhesive.

The pressure-sensitive adhesive composition may be prepared by blending other polymer (optional polymer) into the acrylic polymer, if necessary. These random polymers may be blended for the purpose of enhancing the cohesive force of the adhesive, for example. The increase in the cohesive force of the pressure-sensitive adhesive agent can contribute to the improvement of the ability to prevent the penetration of the liquid medicines from the outer edge of the protective sheet (typically, the performance of preventing the penetration of the liquid medicament mainly due to the swelling of the pressure-sensitive adhesive agent into the liquid medium).

The composition of the random polymer is not particularly limited. For example, a polymer containing a carboxylic acid vinyl ester in the monomer composition can be preferably employed. As the carboxylic acid vinyl ester, vinyl acetate or vinyl propionate is preferable, and vinyl acetate is particularly preferable. Specific examples of the polymer containing a carboxylic acid vinyl ester in the monomer composition include a vinyl chloride-based copolymer such as a vinyl chloride / vinyl acetate copolymer, a vinyl chloride / vinyl acetate / acrylic monomer copolymer, a vinyl chloride / vinyl propionate copolymer, / Vinyl acetate copolymer and the like.

The Tg of the random polymer is preferably more than -20 DEG C, more preferably not lower than 0 DEG C, more preferably not lower than 20 DEG C, particularly preferably not lower than 30 DEG C. The upper limit of the Tg is not particularly limited, but an arbitrary polymer having a Tg of 120 deg. C or lower (more preferably 100 deg. C or lower) is usually preferable from the viewpoint of adhesion with the surface of the adherend. For example, a vinyl chloride / vinyl acetate copolymer having a Tg of 40 占 폚 to 70 占 폚 can be preferably employed.

The mass average molecular weight (Mw) of the random polymer may be, for example, about 0.5 x 10 ⁴ to 10 x 10 ⁴ . An arbitrary polymer having an Mw of 0.8 x 10 ⁴ to 5 x 10 ⁴ (more preferably 1 x 10 ⁴ to 3 x 10 ⁴ ) (for example, a vinyl chloride / acetic acid Vinyl copolymer) are preferable.

When the arbitrary polymer (for example, vinyl chloride / vinyl acetate copolymer) is used, the amount thereof may be 30 parts by mass or less based on 100 parts by mass of the acrylic polymer. From the viewpoint of both cohesion and adhesion, it is generally preferred to use 1 to 30 parts by mass (more preferably 5 to 25 parts by mass, for example, 10 to 20 parts by mass) of the optional polymer per 100 parts by mass of the acrylic polymer desirable.

In the technique disclosed in the present specification, the proportion of the acrylic polymer in the solid content (pressure-sensitive adhesive-forming component) in the pressure-sensitive adhesive composition is preferably more than 50% by mass. The proportion of the acrylic polymer is more preferably not less than 70% by mass (for example, not less than 80% by mass) from the viewpoint of highly compatible compatibility with the liquid chemical penetration prevention and peeling workability. In a preferred form, the proportion of the acrylic polymer may be greater than 85% by weight (e.g., greater than or equal to 90% by weight). This form is advantageous in terms of, for example, _increasing the value of P _L / P _H.

The technique disclosed in this specification can be preferably carried out in the form that the solid content (pressure-sensitive adhesive-forming component) of the pressure-sensitive adhesive composition includes a monomer unit derived from a carboxylic acid vinyl ester (hereinafter also referred to as a carboxylic acid vinyl ester unit) have. Such carboxylic acid vinyl ester units can be obtained by, for example, synthesizing an acrylic polymer by polymerizing (typically, solution polymerization) a monomer raw material comprising alkyl (meth) acrylate and a carboxylic acid vinyl ester, Or may be contained in the pressure-sensitive adhesive composition in the form of a monomer unit constituting a homopolymer or copolymer of a carboxylic acid vinyl ester due to mixing of an arbitrary polymer containing an acid ester. As a preferable example of the pressure-sensitive adhesive composition comprising a carboxylic acid vinyl ester unit, an acrylic polymer obtained by polymerizing a monomer raw material comprising an alkyl (meth) acrylate and a carboxylic acid vinyl ester, and a vinyl monomer having a carboxylic acid vinyl ester (For example, a vinyl chloride / vinyl acetate copolymer).

The proportion of the carboxylic acid vinyl ester units in the solid content of the pressure-sensitive adhesive composition may be, for example, 5% by mass or more, and preferably 10% by mass or more. From the viewpoint of enhancing the adhesion to an adherend (for example, a glass substrate) and simultaneously achieving the prevention of the penetration of the chemical solution and the peeling workability at a high level, the above ratio is preferably 20 mass% or more, more preferably 30 mass% More preferable. In addition, even when the above ratio is too high, the adhesion may be lowered, so that the proportion of the vinyl acetate units in the solid content of the pressure-sensitive adhesive composition is preferably 65% , And more preferably 50 mass% or less.

The pressure-sensitive adhesive composition may contain additives such as an antistatic agent, a slip agent, an anti-blocking agent, a leveling agent, a plasticizer, a filler, a colorant (pigment, dye, etc.), a pH adjuster, a dispersant, a stabilizer, Various additives commonly used in the field of pressure-sensitive adhesives such as an antioxidant may be further contained if necessary. When such an additive is used, the blending amount thereof may be set to the same amount as the usual amount of the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer (production of protective sheet) in the application.

As a method of forming the pressure-sensitive adhesive layer on a substrate, for example, there can be cited a method (direct method) in which the pressure-sensitive adhesive composition is applied (typically, applied) (A transfer method) in which the pressure-sensitive adhesive composition is applied and cured on the surface of the substrate to form a pressure-sensitive adhesive layer on the release surface, and the pressure-sensitive adhesive layer is bonded to the substrate and transferred. The curing treatment may be one or two or more treatments selected from drying (heating), cooling, crosslinking, further copolymerization, aging, and the like. For example, a process of merely simply drying a pressure-sensitive adhesive composition containing a solvent (such as a heat treatment) or a process of simply cooling (solidifying) the pressure-sensitive adhesive composition in a heating and melting state may be included in the curing treatment. When the curing treatment includes two or more treatments (for example, drying and crosslinking), these treatments may be performed at the same time or may be performed in multiple steps.

The application and adhesion of the pressure-sensitive adhesive composition can be carried out, for example, by using a coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater or a spray coater. From the standpoint of promoting the crosslinking reaction and improving the production efficiency, the drying of the pressure-sensitive adhesive composition is preferably carried out under heating. Depending on the type of the support to which the pressure-sensitive adhesive composition is applied, for example, a drying temperature of about 40 캜 to 150 캜 may be adopted. After drying, the aging treatment may be carried out to maintain the crosslinking reaction at about 40 to 60 캜 so that the crosslinking reaction proceeds further. The aging time may be appropriately selected according to the desired degree of crosslinking or the progress of the crosslinking reaction, and may be, for example, about 12 hours to 120 hours, typically about 12 hours to 72 hours.

The thickness of the pressure-sensitive adhesive layer is not particularly limited and can be appropriately adjusted according to the purpose. The thickness of the pressure-sensitive adhesive layer may be, for example, about 1 m to 100 m. A thickness suitable for adhesion with the surface of the adherend is 2 占 퐉 or more, more preferably 3 占 퐉 or more (for example, 5 占 퐉 or more, typically 7 占 퐉 or more). From the viewpoint of peeling workability, the thickness of the pressure-sensitive adhesive layer is preferably 40 占 퐉 or less, and typically 30 占 퐉 or less. The thickness of the pressure-sensitive adhesive layer is preferably not too large from the viewpoint of inhibiting the infiltration of the chemical liquid due to the swelling of the pressure-sensitive adhesive.

The arithmetic average surface roughness of the surface of the pressure-sensitive adhesive layer (adhesive surface, that is, the adhered surface to the adherend) is preferably 1 m or less, and preferably 0.05 m to 0.75 m (for example, approximately 0.05 m to 0.5 m, 0.1 mu m to 0.3 mu m). When the smoothness of the adhesive surface is increased, the adhesion between the adhesive surface and the surface of the adherend is improved. This makes it possible to prevent the penetration of the chemical liquid from the interface between the pressure-sensitive adhesive and the adherend more easily. In addition, since the pressure sensitive adhesive layer having a high smoothness is less prone to stress when peeled from the surface of the adherend, a phenomenon such that a part of the pressure sensitive adhesive is broken due to local stress and remains on the adherend side can be more avoided. Therefore, the protective sheet having such a pressure-sensitive adhesive layer on a substrate can be easily peeled off from the adherend without causing contamination such as residual adhesive on the surface of the adherend.

The arithmetic mean surface roughness of the adhesive surface can be measured using a general surface roughness measuring apparatus (for example, a non-contact three-dimensional surface shape measuring apparatus of Veeco, type "Wyko NT-3300").

The surface on the side where the pressure-sensitive adhesive layer in the substrate is disposed is subjected to a surface treatment such that the surface state (surface roughness of the pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer is not affected (i.e., the arithmetic average surface roughness of the pressure- . For example, the base material preferably has an arithmetic average surface roughness of the adhesive layer side surface of 1 m or less, and preferably 0.05 m to 0.75 m (for example, approximately 0.05 m to 0.5 m, typically approximately 0.1 m to 0.3 m) More preferable. With such a constitution, the smoothness of the adhesive surface also increases.

The gel fraction of the pressure-sensitive adhesive constituting the protective sheet is not particularly limited and may be 20 mass% or more, for example. From the viewpoints of improvement in peeling workability (suppression of high-speed peeling strength), it is usually preferable that the gel fraction is 25 mass% or more. As the gel fraction of the pressure sensitive adhesive increases, the ability to prevent the penetration of the liquid medicines from the outer edge of the protective sheet (typically, the ability to prevent the liquid medication from ingressing due to the swelling of the pressure sensitive adhesive mainly in the liquid medium) is improved. In addition, the cohesive force of the pressure sensitive adhesive increases, and contamination such as residual adhesive is less likely to occur when the protective sheet is peeled off. From this viewpoint, it is more preferable that the gel fraction of the pressure-sensitive adhesive is 27 mass% or more (for example, 30 mass% or more).

The upper limit of the gel fraction is not particularly limited, but is typically 80 mass% or less, preferably 70 mass% or less, more preferably 60 mass% or less (for example, 55 mass% or less). If the gel fraction is too high, the adhesion with the surface of the adherend tends to deteriorate depending on the constitution of the pressure-sensitive adhesive, and the chemical liquid may easily enter from the interface between the pressure-sensitive adhesive and the adherend. The technique disclosed in this specification can be preferably carried out also in the form that the gel fraction of the pressure-sensitive adhesive is 50 mass% or less (typically 45 mass% or less, for example, 40 mass% or less) from the viewpoint of the above adhesion.

The gel fraction can be controlled by the copolymerization composition of the acrylic polymer (for example, the use of a functional group-containing monomer or a polyfunctional monomer), molecular weight, cross-linking agent, and other additives.

The gel fraction was obtained by putting a measurement sample of weight W1 in a porous sheet made of tetrafluoroethylene resin and immersing it in ethyl acetate for one week at room temperature and then drying the measurement sample to determine the weight W2 of ethyl acetate- And substituting W1 and W2 into the following formula: gel fraction [%] = W2 / W1 * 100;

More specifically, the gel fraction can be measured by the following method. That is, about 0.1 g of the measurement sample was packed in a bag shape with a porous sheet made of tetrafluoroethylene resin having an average pore diameter of 0.2 탆, and the inlet was bundled with a green filter. The total mass (Wa (mg)) of the tetrafluoroethylene resin porous sheet and the combustion chamber is measured in advance. Then, the package mass (total mass of the pressure-sensitive adhesive layer and the package) Wb (mg) is measured. The package is placed in a 50-mL screw tube (using one screw tube per package), and the screw tube is filled with ethyl acetate. After standing at room temperature (typically 23 ° C) for 7 days, the package is taken out and dried at 120 ° C for 2 hours, and the mass Wc (mg) of the package after drying is measured. The gel fraction (%) of the pressure-sensitive adhesive layer is calculated by dividing the Wa, Wb and Wc by the following formula:

Gel fraction [%] = (Wc-Wa) / (Wb-Wa) 100

. As the porous sheet made of the tetrafluoroethylene resin, "Nitoflon (registered trademark) NTF1122" available from Nitto Denko Corporation can be used. The same method can be adopted in the following embodiments.

The protective sheet disclosed in this specification has a low peel strength (P _L ) of 0.1 N / 20 mm or more (typically 0.2 N / mm or less) measured at 30 minutes after peeling on a glass plate at a peel angle of 180 ° and a tensile rate of 300 mm / 20 mm or more, for example, 0.25 N / 20 mm or more). The protective sheet exhibiting such a low peel strength (P _L ) is excellent in adhesion to a glass plate or other adherend (material to be treated). Therefore, the penetration of the chemical liquid from the interface between the pressure-sensitive adhesive and the adherend can be effectively prevented. The upper limit of the low-speed peel strength (P _L ) is not particularly limited, but it is usually appropriate that the low-speed peel strength (P _L ) is 5 N / 20 mm or less (for example, 3 N / 20 mm or less, typically 2 N / .

The low-speed peel strength (P _L ) can be measured by the following method. The protective sheet provided for the measurement is cut into a rectangular shape of 20 mm x 60 mm in which the MD (Machine Direction) of the substrate is oriented in the longitudinal direction to prepare a test piece. The pressure-sensitive adhesive layer side of this test piece was attached to a glass substrate by reciprocating one roller of 2 kg. The test piece was held under the environment of 25 占 폚 and 50% RH for 30 minutes and then subjected to a tensile tester (manufactured by Shimadzu Seisakusho Co., Ltd., trade name "Tensilon" Under the conditions of a peel angle of 180 ° and a tensile rate of 300 mm / min. As the glass substrate, "MICROSLIDE GLASS" available from Matsunami Glass Co., Ltd. can be used. The same method can be adopted in the following embodiments.

The protective sheet disclosed in this specification also has a high peel strength (P _H ) measured at a peel angle of 180 ° and a tensile speed of 10 m / min after 30 minutes by being attached to a glass plate of 3 N / 20 mm or less (more preferably 2.5 N / 20 mm or less, for example, 2 N / 20 mm or less, typically 1.5 N / 20 mm or less). The protective sheet showing such a high peel strength (P _H ) is less prone to rupture (fragmentation) or residual adhesive of the protective sheet when peeled off from the glass plate or other adherend (article to be treated), and the load applied to the adherend is small . Therefore, the peeling workability is excellent. The lower limit of the high peel strength (P _H ) is not particularly limited, but it is usually appropriate that the high peel strength (P _H ) is 0.05 N / 20 mm or more (typically 0.1 N / 20 mm or more).

The measurement of the high-speed peel strength (P _H ) can be carried out in the same manner as the measurement of the low-speed peel strength (P _L ) except that the tensile speed is 10 m / min. The same method can be adopted in the following embodiments.

The protective sheet disclosed in this specification preferably has a ratio (P _L / P _H ) of the low peel strength (P _L ) to the high peel strength (P _H ) of more than 0.5, more preferably 1 or more. A protective sheet having a P _L / P _H of more than 0.5 is light in peeling at a high speed as compared with a heavy peeling at a low speed. Therefore, it is possible to balance both the prevention of the penetration of the chemical liquid and the peeling workability. For example, even if the gel fraction of the pressure-sensitive adhesive is less than 60 mass% (typically 50 mass% or less), elongation of the protective sheet or adhesive residue is unlikely to occur when the protective sheet is peeled off. In one preferred form of the protective sheet disclosed in this specification, P _L / P _H is 2 or more (more preferably 3 or more, for example, 4 or more). According to such a protective sheet, it is possible to achieve both the prevention of chemical solution penetration and the peeling workability at a higher level.

The protective sheet disclosed herein has a strength (T _M25 ) at 10% stretching to a MD (Machine Direction) at 25 ° C and a tensile strength of 10% at a temperature of 25 ° C and a TD (Transverse Direction; And at least one of the strength (T _T25 ) at the time of stretching is preferably 1 N / cm to 25 N / cm. It is more preferable that both T _M25 and T _T25 satisfy the numerical range of the strength at the time of 10% stretching as described above. When the tensile strength (T _M25 , T _T25 ) at 10% stretching is 1 N / cm or more, the protective sheet has a suitable hardness and is therefore easy to handle. For example, it is difficult to cause wrinkles, peeling, twisting, or the like when adhering to an adherend, and it is easy to adhere. Further, since the protective sheet has a predetermined strength or more, the problem that the protective sheet is broken at the time of peeling is prevented, and the peeling workability is good. The strength (T _M25 , T _T25 ) at 10% stretching is preferably not more than 22 N / cm (for example, not more than 20 N / cm, typically not more than 18 N / cm). Since the strength (T _M25 , T _T25 ) of the protective sheet at 10% stretching is 25 N / cm or less, even if the surface of the adherend has a step, it can be well followed to its surface shape, great.

The tensile strength at 10% elongation was measured at a temperature of 25 占 폚 in accordance with JIS K7127 along a measuring direction (T _M25 , T _T25 ) and a test piece having a width of 10 mm at a tensile rate of 300 mm / min Refers to the tensile strength at 10% elongation.

The protective sheet disclosed in this specification has a flexural rigidity value (D _M25 ) for MD at 25 ° C and a bending stiffness value for TD at the same temperature from the viewpoint of peeling workability and handling property of the protective sheet D _T25 ) is preferably at least 1.5 × 10 ^-5 Pa · m ³ (for example, at least 2 × 10 ^-5 Pa · m ³ , typically at least 3 × 10 ^-5 Pa · m ³ ) . In addition, the surface shape from the viewpoints of followability at least one of D _M25 and ^{_{D T25 10 × 10 -5 Pa ·}} m 3 or less (for example, 9.5 × 10 ^-5 Pa · m ³ or less, typically from 9 × 10 ^{- 5} Pa · m ³ or less). It is more preferable that both of D _M25 and D _T25 satisfy the numerical ranges of the bending stiffness values described above.

The bending stiffness value (D _M25 ) is determined by the following formula when the thickness of the base material is h and the foaming ratio of the base material is V and the tensile elastic modulus of the protective sheet to MD at 25 캜 is E _M25 :

^{_{D M25 = E M25 h 3/}} 12 (1-V 2);

. The bending stiffness value (D _T25 ) is also obtained by using the tensile modulus of elasticity (E _T25 ) to TD in the same manner as in the case of D _M25 . Further, since the bending stiffness value of the pressure-sensitive adhesive layer is very small as compared with the bending stiffness value of the base material, the bending stiffness value of the protective sheet can be made substantially equal to the bending stiffness value of the base material. Therefore, the flexural rigidity values (D _M25 , D _T25 ) of the protective sheet are values converted into per unit area of the substrate constituting the protective sheet. The cross-sectional area of the substrate is calculated based on the thickness of the substrate. The thickness (h) of the substrate is a value obtained by subtracting the thickness of the pressure-sensitive adhesive layer from the measured value of the thickness of the protective sheet. The Poisson's ratio (V) is a value determined according to the material of the base material (dimensionless number). When the material is a resin, 0.35 can be generally adopted as the value of V.

At least one of the tensile elastic modulus (E _M25 ) to the MD at 25 ° C and the tensile elastic modulus to TD (E _T25 ) at the same temperature is preferably 50 MPa or more (for example, 100 MPa or more , Typically at least 150 MPa). This protective sheet tends to have excellent handling properties under a normal temperature environment. E _M25 and E _T25 of the protective sheet may be 9000 MPa or less (for example, 8000 MPa or less, typically 4000 MPa or less). The bending stiffness value (D _M25 , D _T25 ) of such a protective sheet tends to be an appropriate value. As a result, the surface having a step difference easily tends to be excellent in adhesion.

The tensile modulus (E _M25 , E _T25 ) of the protective sheet was measured by cutting a test piece having a predetermined width along the MD or TD from the protective sheet and measuring the tensile modulus of the MD or the test piece at a temperature of 25 캜 according to JIS K7161 at a tensile rate of 300 mm / TD can be calculated from the linear regression of the stress-strain curve obtained by stretching. Further, since the tensile modulus of the pressure-sensitive adhesive layer is very small as compared with the tensile modulus of the substrate, the tensile modulus of the protective sheet can be almost equal to the tensile modulus of the substrate. Therefore, in the present specification, the tensile modulus of elasticity (E _M25 , E _T25 ) of the protective sheet refers to a value obtained by converting per unit area of the substrate constituting the protective sheet. The cross-sectional area of the substrate is calculated based on the thickness of the substrate. The thickness of the substrate is a value obtained by subtracting the thickness of the pressure-sensitive adhesive layer from the measured value of the thickness of the protective sheet.

As described above, the strength at 10% stretching of the substrate, the flexural rigidity at a predetermined temperature, and the tensile elastic modulus are almost equal to the strength at 10% stretching of the protective sheet, the flexural rigidity at a predetermined temperature and the tensile elastic modulus . Therefore, the protective sheet that satisfies each of the above characteristics can be obtained, for example, by selecting the kind of the substrate (for example, the blending component and the blending ratio), the thickness, and the like.

The protective sheet may be in the form of a protective sheet having a release liner on which a release liner is disposed before use (before attachment to an adherend) on the surface of the pressure-sensitive adhesive layer. When the release liner is disposed on the adhesive surface and the surface (release surface) opposed to the adhesive surface is excellent in smoothness, the smoothness of the surface (pressure-sensitive adhesive surface) of the pressure-sensitive adhesive can be more stably maintained until the protective sheet is used.

As the release liner, various kinds of paper (the surface may be resin-laminated paper), a resin film, and the like can be used without particular limitation. When a resin film is used as the release liner, examples of suitable resin components constituting the resin film include polyolefin resins, polyester resins such as PET, polyamide resins, polycarbonate resins, and polyurethane resins. A release liner including a resin material containing one type of such resin alone, or a release liner including a resin material in which two or more resins (for example, PE and PP) are blended. Such a resin film for a release liner can be produced by suitably adopting a general film molding method as in the resin sheet for a substrate. The structure of the release liner may be a single layer or a multilayer structure of two or more layers.

When a transfer method is adopted as a method of forming a pressure-sensitive adhesive layer on a substrate, the same one may be used for the transfer sheet and the release liner. For example, a base material may be bonded to a pressure-sensitive adhesive layer formed on a release face of a transfer sheet to transfer the pressure-sensitive adhesive layer to the base material, and the transfer sheet may be left on the pressure-sensitive adhesive layer to be used as a release liner. The form in which the transfer sheet serves also as the release liner is preferable from the viewpoints of productivity improvement, material cost reduction, and waste reduction.

The thickness of the release liner is not particularly limited, and may be approximately 5 占 퐉 to 500 占 퐉 (for example, approximately 10 占 퐉 to 200 占 퐉, typically approximately 30 占 퐉 to 200 占 퐉). The release surface of the release liner (the surface disposed in contact with the adhesive surface) may be subjected to a release treatment by a conventionally known release agent (for example, a general silicone system, a long chain alkyl system, a fluorine system, etc.) if necessary. The back surface of the release surface may be subjected to a peeling treatment or may be subjected to surface treatment other than the peeling treatment or may not be treated.

The arithmetic mean surface roughness of the surface of the releasing liner disposed on the pressure-sensitive adhesive layer is preferably 0.05 탆 to 0.75 탆 (for example, approximately 0.05 탆 to 0.5 탆, typically approximately 0.1 탆 to 0.3 탆). Thereby, the smoothness of the surface of the pressure-sensitive adhesive (pressure-sensitive adhesive surface) can be kept high until the protective sheet is used. The high smoothness of the adhesive surface is advantageous in preventing the penetration of the chemical liquid from the interface between the adhesive and the adherend. It is also preferable from the standpoint of prevention of residual adhesive. For the same reason, in a protective sheet in which the surface of the pressure-sensitive adhesive layer (pressure-sensitive adhesive surface) is brought into contact with the back surface of the substrate to protect the pressure-sensitive adhesive surface until the protective sheet is used, the arithmetic mean surface roughness of the back surface of the substrate is preferably 0.05 to 0.75 (For example, approximately 0.05 탆 to 0.5 탆, typically approximately 0.1 탆 to 0.3 탆).

The protective sheet disclosed in this specification can be used as a protective sheet for protecting a portion of the adherend adhered to a desired portion of the adherend. The pressure sensitive adhesive used for this protective sheet has high adhesion to an adherend. Therefore, the performance of preventing the ingress of a chemical liquid (particularly, an aqueous chemical liquid, typically an acidic chemical liquid) from the interface between the pressure-sensitive adhesive and the adherend at the outer edge of the protective sheet is excellent. Thereby, it is possible to reliably prevent the penetration of the chemical solution into the portion where the chemical solution is not intended to be exposed, and to protect the surface. In addition, since the high adhesiveness and the light fastness at high speed peeling are combined, the protective sheet itself and the adherend are hardly damaged, and the adhesive remains on the adherend surface hardly. Therefore, the peeling workability is excellent.

Taking these characteristics into consideration, the protective sheet disclosed in this specification can be applied to, for example, an etching treatment in which a thickness of a glass is reduced or a glass is dissolved in a chemical solution (etching solution) in order to remove burrs or micro cracks formed on a cross- An etching treatment for partially etching the surface of the metal with a chemical solution (etching solution), a plating treatment for partially plating the connection terminal portion of a circuit board (a printed board, a flexible printed board (FPC), or the like) with a chemical solution And can be suitably used.

Further, for example, when the chemical liquid treatment is performed by attaching the protective sheet to the range including the outer edge of the adherend, when the chemical liquid partially penetrates from the outer edge of the adherend (the outer edge of the area where the protective sheet is adhered) The smoothness of the outer edge (edge) of the adherend may be damaged by the influence of the chemical liquid. If the smoothness of the edge of the adherend is impaired, there may arise a problem that the strength of the adherend is lowered particularly in an adherend such as a glass substrate. The protective sheet disclosed in this specification is excellent in the ability to prevent the penetration of the chemical liquid from the outer edge of the protective sheet, and therefore, the smoothness of the edge of the adherend can be effectively prevented from deteriorating.

<Examples>

Hereinafter, some embodiments according to the present invention will be described, but the present invention is not intended to be limited to those shown in these embodiments. In the following description, &quot; part &quot; and &quot;% &quot; are based on mass unless otherwise specified.

[Production of substrate]

&Lt; Preparation Example 1 &

A film substrate (PP / PE / EPR blend film) A having a thickness of 40 占 퐉 was extruded by a T-die method to obtain a film-shaped substrate (PP / PE / EPR blend film) . A corona discharge treatment was applied to one surface of the substrate A.

As the PP, crystalline homopolypropylene having a resin density of 0.905 and random polypropylene having a resin density of 0.900 were used in a mass ratio of 1: 1. As the PE, a low density polyethylene &quot; Petrosen (registered trademark) 205 &quot; manufactured by TOSOH CORPORATION was used. As the EPR, "TFMER (registered trademark) P0180" manufactured by Mitsui Chemicals, Inc. was used.

&Lt; Preparation Example 2 &

(PE film) B1 having a thickness of 60 占 퐉 was obtained by molding low-density polyethylene ("Petrocene (registered trademark) 180" manufactured by Tosoh Corporation) under the condition of a die temperature of 160 ° C by an inflation molding machine. Corona discharge treatment was applied to one surface of the substrate B1.

&Lt; Preparation Example 3 &

(PE film) B2 having a thickness of 40 占 퐉 was obtained by molding low-density polyethylene ("Petrocene (registered trademark) 180" manufactured by Tosoh Corporation) under the condition of a die temperature of 160 ° C by an inflation molding machine. A corona discharge treatment was applied to one side of the substrate B2.

[Preparation of pressure-sensitive adhesive composition]

&Lt; Preparation Example 1 &

263 parts of toluene as a polymerization solvent, 100 parts of 2-ethylhexyl acrylate (2EHA) as a monomer raw material, 80 parts of vinyl acetate (VAc) and 100 parts of acrylic acid (AA) were added to a reaction vessel equipped with a stirrer, a thermometer, ) And 0.3 part of benzoyl peroxide (BPO, "NIPHER (registered trademark) BW" manufactured by Nippon Oil Co., Ltd.) as a peroxide-based polymerization initiator, and nitrogen reflux was carried out at room temperature for 1 hour. Subsequently, the temperature of the container contents was raised to 63 캜, and polymerization was carried out in a nitrogen stream for 6 hours. Thereafter, the temperature of the container contents was raised to 80 캜 and aged for 6 hours to obtain a solution of the acrylic polymer A. To 100 parts of the solid content of the acrylic polymer solution thus obtained, 0.3 part of polyoxyethylene alkyl ether phosphate ("Phospholone (registered trademark) RL-210" manufactured by Tohoku Kagaku Kogyo Co., Ltd., HLB 5.4) And 5 parts of an isocyanate crosslinking agent ("Coronate (registered trademark) L", manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent were blended, and toluene was added so as to have a solid content of 20% to obtain a pressure- The Tg of the acrylic polymer A calculated from the Fox equation is -32 占 폚.

&Lt; Preparation Example 2 &

(Registered trademark) RM-410 (manufactured by Toho Chemical Industry Co., Ltd., polyoxyethylene alkyl ether phosphoric acid ester, HLB (trade name) manufactured by Toho Chemical Industry Co., Ltd.) was used in place of 0.3 part of "Phosphanol 5.8) was used as a peel adjustment agent. In the other respects, the pressure-sensitive adhesive composition B was obtained in the same manner as in Production Example 1.

&Lt; Preparation Example 3 &

In Production Example 2, 2 parts of polyoxyethylene stearylamine ("NAIMIN (registered trademark) S-204", HLB 8.0) as a peeling adjustment agent was added to 100 parts of the solid content of the acrylic polymer A solution, 15 parts of a vinyl chloride-based copolymer (Tg 64 DEG C, weight average molecular weight: about 18,000) were further blended. In the other respects, the pressure-sensitive adhesive composition C was obtained in the same manner as in Production Example 2.

&Lt; Preparation Example 4 &

5 parts of an isocyanate crosslinking agent ("Coronate (registered trademark) L", manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent was blended with 100 parts of the solid content of the acrylic polymer A solution obtained in the same manner as in Production Example 1, To obtain a pressure-sensitive adhesive composition D. &lt; tb &gt; &lt; TABLE &gt;

&Lt; Production Example 5 &

2 parts of an epoxy crosslinking agent ("TETRAD (registered trademark) -C" manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a crosslinking agent was blended with 100 parts of the solid content of the acrylic polymer A solution obtained in the same manner as in Production Example 1, %, To obtain a pressure-sensitive adhesive composition E. &lt; tb &gt; &lt; TABLE &gt;

&Lt; Production Example 6 &

182 parts of toluene as a polymerization solvent, 100 parts of 2-ethylhexyl acrylate (2EHA) as a monomer raw material, and 2 parts of 2-hydroxyethyl acrylate (2 parts by weight) were added to a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel, HEA) and 0.2 part of 2,2'-azobis (2-methylpropionitrile) (manufactured by Wako Pure Chemical Industries, Ltd., AIBN) as an azo-based polymerization initiator were put and nitrogen reflux was conducted at room temperature for 1 hour . Then, the temperature of the container contents was raised to 61 DEG C, and polymerization was carried out in a nitrogen stream for 5 hours. Thereafter, the temperature of the container contents was raised to 70 캜 and aged for 5 hours to obtain a solution of the acrylic polymer F. As a crosslinking agent, 4 parts of an isocyanate crosslinking agent ("Coronate (registered trademark) L" manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, 4 parts of dioctyl tin dilaurate as a crosslinking accelerator , 0.02 part of "Envisizer OL-1" manufactured by Tokyo Fine Chemical Co., Ltd.), acetyl acetone as a solvent was added so as to be 4% of the total solvent amount, toluene was added so that the solid content became 20% Composition F was obtained. The Tg of the acrylic polymer F calculated from the Fox equation is -68.3 占 폚.

[Production of protective sheet]

<Example 1>

Two substrates A were prepared. A pressure-sensitive adhesive composition A was coated on the corona-treated surface of the first substrate A and dried at 80 DEG C for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 mu m. The non-corona treated surface of the second substrate A as a release liner was bonded to this pressure-sensitive adhesive layer and aged at 50 캜 for 2 days (48 hours) to obtain a protective sheet according to this example.

<Example 2>

A polyethylene terephthalate film ("Lumirror (registered trademark) S-10" manufactured by Toray Industries, Inc.) having a thickness of 38 mu m was prepared as the base material C. A pressure-sensitive adhesive composition B was coated on one side of the base material C and dried at 80 DEG C for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 mu m. This pressure-sensitive adhesive layer was laminated with a silicone-treated surface of a 38 占 퐉 -thick polyethylene terephthalate film ("Diapholle (registered trademark) MRF38" manufactured by Mitsubishi Kagaku Polyester Film Co., Ltd.), one side of which was treated with a silicone- And aged at 50 DEG C for 2 days to obtain a protective sheet according to this example.

<Example 3>

A pressure-sensitive adhesive composition C was coated on one side of the substrate C and dried at 80 DEG C for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 mu m. This pressure-sensitive adhesive layer was laminated with a silicone-treated surface of a 38 占 퐉 -thick polyethylene terephthalate film ("Diapholle (registered trademark) MRF38" manufactured by Mitsubishi Kagaku Polyester Film Co., Ltd.), one side of which was treated with a silicone- And aged at 50 DEG C for 2 days to obtain a protective sheet according to this example.

<Example 4>

Two substrates B1 were prepared. A pressure-sensitive adhesive composition C was coated on the corona-treated surface of the first substrate B1 and dried at 80 DEG C for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 mu m. The non-corona treated surface of the second substrate B1 as a release liner was bonded to the pressure-sensitive adhesive layer and aged at 50 DEG C for 2 days to obtain a protective sheet according to this example.

<Example 5>

Two substrates B2 were prepared. A pressure-sensitive adhesive composition D was coated on the corona-treated surface of the first substrate B2 and dried at 80 DEG C for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 mu m. The non-corona treated side of the second substrate B2 as a release liner was bonded to this pressure-sensitive adhesive layer, and aged at 50 DEG C for 2 days to obtain a protective sheet according to this example.

<Example 6>

A protective sheet according to this example was obtained in the same manner as in Example 4 except that the pressure-sensitive adhesive composition E was used in place of the pressure-

<Example 7>

A protective sheet according to this example was obtained in the same manner as in Example 4 except that the pressure-sensitive adhesive composition F was used in place of the pressure-sensitive adhesive composition C and the thickness of the pressure-sensitive adhesive layer was set to about 20 탆.

[Measurement of gel fraction]

Approximately 0.1 g of the pressure sensitive adhesive collected from the protective sheet after aging was applied to a porous sheet made of tetrafluoroethylene resin (trade name: "Nitoflon (registered trademark) NTF1122" manufactured by Nitto Denko Corporation) Packed in a bag shape, and the total mass Wb of the package was weighed. The package was immersed in a solvent (ethyl acetate), allowed to stand at 23 占 폚 for 7 days, dried at 120 占 폚 for 2 hours, and the mass (Wc) of the package after drying was measured. The Wa, Wb, and Wc were substituted into the following equations to calculate the gel fraction of the pressure-sensitive adhesive.

Gel fraction [%] = (Wc-Wa) / (Wb-Wa) 100

[Evaluation for preventing chemical solution penetration]

A glass substrate made by Matsunami Glass Co., Ltd. "MICROSLIDE GLASS" (length 76 mm, width 26 mm, thickness 1.3 mm) was prepared and its edge (outer edge) was visually observed, A straight shape without irregularities). A protective tape was attached to each of the entire surface and the back surface of the glass substrate to prepare a test sample. The sample was allowed to stand for 30 minutes.

A 100 mL of a 20% aqueous solution of hydrofluoric acid (HF) was poured into a plastic container having a length of 100 mm, a width of 100 mm and a height of 30 mm. The sample after 30 minutes was settled therein and allowed to stand for 3 hours.

After 3 hours had elapsed, a sample was taken out from the 20% hydrofluoric acid aqueous solution using a tweezers made of polyethylene, sufficiently washed with water, and then dried at 50 DEG C for 2 hours.

After drying, the protective sheet was peeled off from the glass substrate, and the front and back surfaces of the glass substrate (that is, the area where the protective sheet was attached) were visually observed, and the presence or absence of chemical liquid penetration was evaluated at the following two levels.

&Amp; cir &amp;: No dissolution due to the penetration of the chemical solution was observed on either the front surface or the back surface.

X: Dissolution by penetration of a chemical solution was confirmed on at least one of the front surface and the back surface.

The operation of peeling the protective sheet from the glass substrate was carried out by manually peeling the protective sheet in the 180 ° direction at a tensile speed of about 10 m / min under the measurement environment of 25 ° C and 50% RH.

[Evaluation of smoothness of edge]

The edge of the glass substrate after the protective sheet was peeled off in the chemical liquid penetration prevention evaluation was visually observed again and the smoothness of the edge was evaluated at the following two levels.

A: The edge had a straight shape without irregularities.

X: Unevenness was seen on the edge.

[Evaluation of peeling workability]

The evaluation of the workability when the protective sheet was peeled off from the glass plate in evaluation of the chemical solution penetration prevention was evaluated at the following two levels.

∘: It was possible to smoothly peel off, and no elongation or break of the protective sheet was observed.

X: The peeling was heavy and the elongation of the protective sheet was seen.

[Measurement of low-speed peel strength]

The low-speed peel strength of the glass was measured under the following conditions.

Measurement environment: 25 ° C, 50% RH

Size of specimen: width 20mm, length 60mm

Tensile speed: 300 mm / min

Peeling direction: 180 °

Size of protective sheet: 20 mm x 60 mm (MD was cut in the longitudinal direction)

Adherend: glass substrate made by Matsunami Glass High Co., Ltd., trade name "MICROSLIDE GLASS", size 1.3 mm × 65 mm × 165 mm

Method of operation: A protective sheet was pressed on the surface of the adherend, and the low-speed peel strength (P _L ) was measured after standing for 30 minutes in the measurement environment. The pressing was performed by reciprocating one roller of 2 kg.

[High-speed peel strength measurement]

The high-speed peel strength (P _H ) of the glass was measured in the same manner as the low-speed peel strength measurement except that the tensile speed was set at 10 m / min.

The evaluation results of the protective sheet relating to Examples 1 to 7 are shown in Table 1.

Low speed peel strength As shown in Table 1 is 0.1N / 20mm or higher (P _L) (more specifically, is 0.25N / 20mm or greater), and high-speed peel strength (P _H) 3N / 20mm or less (more specifically, 1.5 N / 20 mm or less), and the protective sheets of Examples 1 to 4 in which the gel fraction was in the range of 25% to 70% were all excellent in preventing the penetration of the chemical solution, having high edge smoothness and good peeling workability. In any case of these protective sheets or in the measurement of the high-speed peel strength, the adhesive remnant to the adherend surface was not recognized.

On the other hand, in Example 5 in which the high peel strength (P _H ) was too high, the elongation of the protective sheet was recognized in the peeling workability evaluation. Further, in the high-speed peel strength measurement, the adhesive remained on the surface of the adherend was recognized. The protective sheet of Examples 6 and 7 had a low peel strength (P _L ) of 0.1 N / 20 mm or more, but the adhesion to the adherend was insufficient because the gel fraction was too high and the performance to prevent the penetration of the drug solution onto the glass surface And poor performance of keeping the edge smooth. In addition, the protective sheet of Example 6 had a high peel strength (P _H ) at too high a level, which made it difficult to peel off workability.

While specific embodiments of the present invention have been described in detail hereinabove, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and variations of the embodiments described above.

1: substrate
2: Pressure-sensitive adhesive layer
3: Liner
4: Protective sheet

Claims (6)

A protective sheet for chemical liquid treatment comprising a base material and a pressure-sensitive adhesive layer disposed on one side of the base material,
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive mainly comprising an acrylic polymer,
The chemical solution treatment protection sheet is attached to the glass plate 30 minutes after peeling angle of 180 °, a tensile speed of 300mm / low speed peel strength is measured in terms of minutes (P _L) is 0.1N / 20mm or more,
The protective sheet for chemical liquid treatment has a high peel strength (P _H ) of 3 N / 20 mm or less measured at a peel angle of 180 ° and a tensile speed of 10 m / min after 30 minutes from adhering to a glass plate,
Wherein the acrylic pressure-sensitive adhesive has a gel fraction of 25 mass% or more and 70 mass% or less. The sheet according to claim 1, wherein the ratio (P _L / P _H ) of the low peel strength (P _L ) to the high peel strength (P _H ) is greater than 0.5. The protective sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition comprising a release-adjusting agent. The protective sheet for treating a chemical liquid according to any one of claims 1 to 3, wherein the acrylic pressure-sensitive adhesive contains a monomer unit derived from a carboxylic acid vinyl ester at a ratio higher than 20 mass%. The acrylic polymer according to any one of claims 1 to 4, which is synthesized by polymerizing a monomer raw material comprising an alkyl (meth) acrylate and a carboxylic acid vinyl ester,
Wherein the content of the carboxylic acid vinyl ester in the monomer raw material is higher than 20 mass%. The protective sheet for chemical liquid treatment according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition comprising the acrylic polymer and an isocyanate-based crosslinking agent.

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